JP2018150414A - Hot-pressed molding of chemically modified lignocellulose and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot pressed molding of chemically modified lignocellulose.SOLUTION: In the hot pressed molding of chemically modified lignocellulose, the chemically modified lignocellulose has the characteristics of (a) and (b). The characteristic (a)(a-1) some hydroxyl groups existing in lignocellulose is half-esterified by a carboxyl group containing acyl group, or (a-2) some hydroxyl groups existing in lignocellulose is etherified by a carboxyl alkyl group, and the characteristic (b)(b-1) the degree of substitution of hydrogen atoms of hydroxyl groups in the half-esterified lignocellulose is 0.01-0.4, or (b-2) the degree of substitution of hydrogen atoms of hydroxyl groups in the esterified lignocellulose is 0.01-0.4.SELECTED DRAWING: None

Description

  The present invention relates to a hot-pressed product of chemically modified lignocellulose and a method for producing the same.

  The hot-press molded product of the chemically modified lignocellulose of the present invention can be produced by subjecting the chemically-modified lignocellulose fiber to hot-pressure processing (hot-press molding).

  Lignocellulose is a complex hydrocarbon polymer (natural polymer mixture) that constitutes the tree cell wall. It is known that lignocellulose is mainly composed of polysaccharides cellulose, hemicellulose and lignin which is an aromatic polymer.

Reference example 1 :
Review Article Conversion of Lignocellulosic Biomass to Nanocellulose:
Structure and Chemical Process HV Lee, SBA Hamid, and SK Zain,
Scientific World Journal Volume 2014, Article ID 631013, 20 pages,
http://dx.doi.org/10.1155/2014/631013
Reference example 2 :
New lignocellulose pretreatments using cellulose solvents:
A review, Noppadon Sathitsuksanoh, Anthe George and YH Percival Zhang,
J Chem Technol Biotechnol 2013; 88: 169-180
Natural lignocellulose has a structure in which lignin and hemicellulose are filled in the gap between cellulose microfibril bundles (cellulose nanofibers: CNF), which is a basic skeleton. This structure can be said to be a nanocomposite using CNF as a filler and lignin / hemicellulose as a matrix.

  Until now, research on the creation of nanocomposites utilizing the thermoplasticity of the matrix while maintaining the crystallinity of cellulose using the nanostructure of wood has been carried out.

  In Non-Patent Document 1 of the present inventors, a slurry of Chemi-Thermo-Mechanical Pulp (CTMP) having a lignin content of 28 mass% is treated with a grinder, and the fiber diameter is 20 nm to 1 μm. It is described that microfibrillated lignocellulosic fibers were prepared and then filtered, dried and hot-pressed to obtain a hot-pressed product.

  In the non-patent document 2 of the present inventors, bleached chemi-thermo-mechanical pulp (BCTMP) is produced by a grinder with the aim of creating a thermoplastic nanocomposite using the structure of the tree cell wall. It is described that when lignocellulose nanofibers (ligno CNF) were obtained and then subjected to selective chemical modification (n-octanoylation) on the surface of this ligno CNF, the thermoplasticity was greatly improved.

  Patent Document 1 of the present inventors includes chemically modified lignocellulose (α-position chemically modified lignocellulose) in which the α-position of the phenylpropane unit constituting lignin in lignocellulose is partially chemically modified, and α-position chemical modification. Lignocellulose (lignocellulose double-modified) in which the hydroxyl groups of cellulose and hemicellulose constituting lignocellulose are further partially chemically modified is disclosed, and hot-pressed bodies of these chemically modified lignocellulose are also disclosed.

  In the hot-press molded body disclosed in Non-Patent Document 1, there is room for improvement in its manufacturing method such as pulp fibrillation step, dry microfibrillated lignocellulose fiber manufacturing step, and hot-pressure molding conditions.

  Moreover, it was found that the hot-press molded body disclosed in Non-Patent Document 2 has room for improvement in terms of strength from the test results of the present inventors.

  Further, in the hot-press molded body disclosed in Patent Document 1, there is room for improvement in the chemical modification group, chemical modification method, and strength characteristics of the hot-press molded body of lignopulp or fibrillated lignopulp.

  On the other hand, regarding the chemical modification of cellulose and pulp, in order to improve the defibrating properties of cellulose and the affinity and miscibility between cellulose and resin in the production of fiber reinforced resin composites containing microfibrillated cellulose and resin. Various chemically modified cellulose and lignocellulose fibers and techniques for producing them have been studied and published.

  In Patent Document 2 of the present inventors, a plant fiber is esterified with alkanoyl chloride such as octanoyl chloride, or half-esterified with alkyl or alkenyl succinic anhydride and then microfibrillated to chemically modified microfibril. Disclosed is a method for producing modified plant fibers, as well as chemically modified microfibrillated plant fibers produced by this method.

  Patent Document 3 of the present inventors discloses a resin composition containing microfibrillated plant fibers chemically modified with alkyl or alkenyl succinic anhydride.

  In Patent Document 4 of the present inventors, plant fibers are modified with an alkyl or alkenyl succinic anhydride in a swellable liquid, and a resin composition containing microfibrillated plant fibers is produced from the chemically modified fibers. A method is disclosed.

  In Patent Document 5, a part of the hydroxyl group of cellulose is half-esterified with a polybasic acid anhydride, a carboxy group is introduced, and the half-esterified cellulose is made into fine fibers, whereby the CNF into which the carboxy group is introduced is obtained. A method of manufacturing is disclosed.

  Patent Document 6 of the present inventors discloses a resin composition containing CNF in which a part of hydroxyl groups of CNF is modified with a substituent having a carboxy group and a resin, and a method for producing the same.

  Patent Document 7 discloses a surface acylated cellulose fiber or surface acylated lignocellulose having an acyl group substitution degree of 0.01 to 0.5, and a compounding material for plastics containing the same.

  Patent Document 8 discloses fine cellulose fibers modified with a carboxymethyl group.

  However, these chemically modified plant fibers, chemically modified celluloses, chemically modified lignocelluloses and these fibrillated fibers (nanoized fibers) described in Patent Documents 2 to 8 exhibit plasticity when compressed under heating, Patent Documents 2 to 8 do not disclose that a hot-pressed product can be obtained by hot-pressing.

High-strength nanocomposite based on fibrillated chemi -thermomechanical pulp, Kentaro Abe, Fumiaki Nakatsubo, Hiroyuki Yano, Composites Science and Technology 69 (2009) 2434-2437 Creation of thermoplastic nanocomposites using cell wall nanostructures, Yuta Watanabe, Masato Ando, Kentaro Abe, Fumiaki Nakatsubo, Hiroyuki Yano, Abstracts of Annual Meeting of the Wood Society of Japan Vol.6414 Page.NO.Z14-01-1100 , (2014.03.03)

JP 2016-169382 A JP 2011-213754 A (Patent No. 5540176) JP 2012-214563 A (Patent No. 5757765) Re-published patent WO2013 / 133093 (Patent No. 5496435) JP 2009-293167 A JP 2012-229350 A (Patent No. 5777779) Japanese Patent Laid-Open No. 9-221501 Japanese Patent Laid-Open No. 10-251301

  The present inventors have made various studies in order to produce a hot-pressed product of chemically modified lignocellulose (also referred to as chemically modified lignocellulose) that is easy to produce and excellent in physical properties such as strength properties. .

  An object of the present invention is to provide a hot-pressed product of chemically modified lignocellulose which is obtained by an easy method and has excellent physical properties, and a method for producing the same.

  In order to solve the above problems, the present inventors have made various studies on the fiber diameter of lignocellulose fiber to be chemically modified, the type of chemical modification group, and the method of hot-pressing the chemically modified lignocellulose fiber.

  As a result, it was found that the lignocellulose fiber modified with a specific chemical modification group exhibits thermoplasticity even with a small modification degree. The present inventors have found that a hot-press molded body having a light weight and high strength characteristics and a low linear thermal expansion coefficient can be easily obtained by subjecting this lignocellulose fiber to hot-pressure processing, and completed the present invention.

  Hot press molding means molding into a desired shape through heating and pressurizing steps.

  The hot-press molded body according to the present invention can be obtained by holding the chemically modified lignocellulose under pressure under heating. The hot pressing conditions are usually 100 ° C. or higher and 1 kPa or higher. If the temperature is too low, or if the pressure is too low, the matrix components may not be sufficiently plasticized and the desired shape may not be obtained.

The density of the hot-press molded body according to the present invention is usually about 1.1 to 1.5 g / cm ³ . Conventionally, the heating process in the known papermaking process is at most about 120 ° C., and the density of the obtained paper is at most about 1.0 g / cm ³ , although the pressure in the pressing process is unknown. Therefore, it can be seen that in the known papermaking process, adhesion due to plasticization of the constituent components (plant fibers) does not occur.

  The present invention relates to a hot-press molded body and a method for producing the same.

  In detail, it is related with the hot-press-molding body of the chemically modified lignocellulose which has the characteristic of (a) and (b) mentioned later, and its manufacturing method.

Definition of Terms In this specification, the following terms have the following meanings.

  Lignocellulose (or LC): means a substance in which lignin and cellulose are present in plants regardless of the lignin content, or / and a mixture of lignin and cellulose.

  Pulp: A product obtained by separating plant fibers contained in plants such as wood, bamboo, and rice straw, and containing cellulose or / and lignocellulose.

  Ligno pulp (or LP): means pulp containing lignocellulose.

Item 1.
A hot-pressed product of chemically modified lignocellulose,
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4.

Item 2.
The hot-press molded body according to item 1, wherein
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in the lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.1 to 0.4.

Item 3.
The hot-press molded body according to item 1, wherein
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.3.

Item 4.
The hot-press molded body according to any one of Items 1 to 3,
The lignin component content of the chemically modified lignocellulose is 2 to 40% by mass,
Hot-pressed body.

Item 5.
5. The hot-pressure molded body according to any one of items 1 to 4, further comprising a thermoplastic resin.

Item 6.
A method for producing a hot-pressed product of chemically modified lignocellulose,
Comprising a step of compressing a fiber assembly composed of chemically modified lignocellulose fibers under heating,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4.

Item 7.
The method for producing a hot-pressed article according to Item 6,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in the lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.1 to 0.4.

Item 8.
The method for producing a hot-pressed article according to Item 6,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.3.

Item 9.
The method for producing a hot-pressed body according to any one of Items 6 to 8,
The average fiber diameter of the chemically modified lignocellulose fiber is 20 nm to 50 μm,
A method for producing a hot-pressed product.

Item 10.
The method for producing a hot-press molded body according to any one of Items 6 to 9,
The lignin component content of the chemically modified lignocellulose fiber is 2 to 40% by mass,
A method for producing a hot-pressed product.

Item 11.
The method for producing a hot-pressed body according to any one of Items 6 to 10,
A method for producing a hot-pressed product, wherein a temperature at which the fiber assembly composed of the chemically modified lignocellulose fiber is heated is 160 to 240 ° C, and a pressure at which the fiber assembly is compressed is 30 to 100 MPa.

Item 12.
A method for producing a hot-press molded body according to any one of claims 6 to 11,
A method for producing a hot-pressed product, wherein a fiber assembly further comprising a thermoplastic resin is used as a fiber assembly composed of chemically modified lignocellulose fibers.

Item 13.
A method for producing a hot-pressed product of chemically modified lignocellulose,
A method for producing a hot-pressed product, comprising the following first step and second step:
(1) First step :
(A-1) In lignocellulose fiber, the following formula (3):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
A part of the hydroxyl group present in the lignocellulose is reacted with a succinic anhydride or a derivative thereof represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
By half-esterification with a carboxy group-containing acyl group represented by
The step of producing a chemically modified lignocellulose fiber by setting the substitution degree of the hydrogen atom of the hydroxyl group in the lignocellulose to be half-esterified to 0.01 to 0.4,
Or
(A-2) In lignocellulose fiber, the following formula (4):
X- (CH ₂ ) _n -COOH (4)
(In the formula, n represents an integer of 1 to 3. X represents a halogen atom selected from the group consisting of Cl, Br and I.)
Is reacted with a halogenoalkyl carboxylic acid represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
By etherification with a carboxyalkyl group represented by
The step of producing chemically modified lignocellulose fibers by setting the degree of substitution of hydrogen atoms of hydroxyl groups in the lignocellulose to be etherified to 0.01 to 0.4,
(2) Second step :
A step of compressing the fiber assembly made of the chemically modified lignocellulose fiber obtained in the first step under heating.

Item 14.
The method for producing a hot-pressed article according to Item 13,
A method for producing a hot-pressed product, wherein a temperature at which the fiber assembly composed of the chemically modified lignocellulose fiber is heated is 160 to 240 ° C, and a pressure at which the fiber assembly is compressed is 30 to 100 MPa.

  The hot-press molded body of the present invention has a structure in which (i) lignin, chemically modified lignin, hemicellulose, and chemically modified hemicellulose contained in the chemically modified lignocellulosic fiber as a matrix are (ii) It can also be said to be a nanocomposite using cellulose nanofiber (CNF) and chemically modified cellulose as a filler.

  Therefore, the hot-press molded body of the present invention is lightweight, has high strength, and has a low coefficient of linear thermal expansion, like plant fibers.

  The hot-press molded body of the present invention is an interior of a transport aircraft (for example, an automobile, a ship, an aircraft) that is lightweight and requires mechanical strength (for example, high tensile strength and elastic modulus) in addition to the field of application of fiber-reinforced plastic. In addition, it can be preferably used as a casing for an exterior material and an electrical appliance.

  Since the hot-press molded body of the present invention is lighter than metals, for example, when used in a transport aircraft, it is effective in reducing fuel consumption. As a result, the hot-press molded body of the present invention has a reduced exhaust gas and is useful for environmental preservation.

  The hot-press molded body of the present invention can be easily produced by a simple operation of compressing a chemically modified lignocellulose fiber aggregate under heating. Therefore, the hot-press molded body of the present invention has an advantage that it can be manufactured with energy saving as compared with conventional materials (carbon fiber reinforced resin, glass fiber reinforced resin, or metal molded body).

(1) Hot-pressed product of chemically modified lignocellulose
Hot-pressed body (Invention 1)
In the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose has the following properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4.

  In other words, the hot-press molded body of the present invention includes the following embodiment (1) or (2).

Aspect (1)
In the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose has the following properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The hydrogen atom substitution degree of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4.

  The degree of substitution is preferably 0.1 to 0.4.

Aspect (2)
In the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose has the following properties (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4.

  The degree of substitution is preferably 0.01 to 0.3.

Raw material for chemically modified lignocellulose fibers (Invention 9)
The manufacturing method of the chemically modified lignocellulose fiber used for manufacture of a hot-pressing molded object is demonstrated.

  Ligno pulp can be used as a raw material for chemically modified lignocellulose fibers.

  For lignopulp, raw materials derived from plant materials contained in softwood or broadleaf derived wood such as Sitka spruce, pine, cedar, cypress, eucalyptus, acacia, bamboo, hemp, jute, kenaf, bagasse, firewood, beet pomace Lignopulp obtained by treating with a mechanical pulping method, chemical pulping method or a combination of mechanical pulping method and chemical pulping method can be used. As such pulp, various kraft pulps (softwood unbleached kraft pulp (NUKP), softwood oxygen bleached unbleached kraft pulp (NOKP), and softwood bleached kraft pulp (NBKP) containing lignin are preferable. Mechanical pulp (MP) such as (GP), refiner GP (RGP), thermomechanical pulp (TMP), and chemithermomechanical pulp (CTMP) contains lignin and is preferable.

  Lignopulp derived from plant raw materials contains lignocellulose and is mainly composed of cellulose, hemicellulose, and lignin.

  In the present invention, a pulp containing a small amount of lignin without completely removing lignin can be used as the lignopulp. Therefore, a pulp containing lignin that can also detect pulp obtained by the above-described various pulping methods is referred to as lignopulp in this specification. Pulp derived from waste paper such as deinked waste paper, corrugated waste paper, magazines, copy paper, etc. can also be used in the present invention as ligno pulp.

  The amount of lignin contained can be quantified by the Klarson method. In the present invention, it is preferable to use lignopulp containing about 2 to 40% by mass of lignin. It is preferable to use lignopulp with the amount of lignin contained more preferably about 2 to 35% by mass, particularly preferably about 2 to 30% by mass.

  In lignopulp, lignin and hemicellulose contained therein function as a matrix of the hot-press molded product of the present invention, and the yield from the raw material is large, the number of steps is small, and the chemical agent required for the production is small. Therefore, it can be advantageously used in the present invention.

  The hot-press molded body of the present invention is manufactured by subjecting chemically modified lignocellulose fiber to hot-pressure processing. This chemically modified lignocellulose fiber is obtained by chemically modifying lignocellulose fiber obtained by defibrating lignopulp. Can be manufactured by.

  The average fiber diameter of the chemically modified lignocellulose fiber is preferably about 20 nm to 50 μm.

  If the fiber diameter is too small, there is a possibility that the retention of the fiber solvent becomes too high and it is difficult to remove the solvent. Moreover, when a fiber diameter is too large, the close_contact | adherence of fibers becomes inadequate at the time of hot-pressure molding, and there exists a possibility that the outstanding intensity | strength may not be expressed. For this reason, the average fiber diameter of the chemically modified lignocellulose fiber is more preferably about 500 nm to 30 μm.

Lignocellulose fiber half ester (Aspect (1))
As described in the aspect (1), in the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose fiber of the raw material has a part of the hydroxyl group present in the lignocellulose represented by the formula (1). It is half-esterified with a carboxy group-containing acyl group.

  This is also referred to as “this half-esterified lignocellulose fiber”.

This half-esterified lignocellulose fiber is converted to lignocellulose fiber by the following formula (3):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
Or a derivative thereof [hereinafter, these acid anhydrides are sometimes referred to as “acid anhydride of formula (3)”. In the lignocellulose to be half-esterified, a part of the hydroxyl groups present in the lignocellulose is half-esterified with a carboxy group-containing acyl group represented by the formula (1). It can manufacture by making the substitution degree of the hydrogen atom of the hydroxyl group of 0.01-0.4.

  Chemical modification of lignocellulosic fiber with acid anhydride of formula (3) involves reacting lignocellulose fiber dispersed in an organic solvent by heating the acid anhydride of formula (3) in the presence of a base, A part of the hydroxyl group present in is half-esterified.

  Here, half ester means that one of two carbonyl groups present in the acid anhydride of formula (3) forms an ester bond with a hydroxyl group in lignocellulose, and the other carbonyl group is a hydroxycarbonyl group. It means the ester in the state.

  Examples of the alkenyl succinic anhydride belonging to the acid anhydride of the formula (3) include compounds having a skeleton derived from an olefin having 4 to 20 carbon atoms and a maleic anhydride skeleton.

  These compounds include pentenyl succinic anhydride, hexenyl succinic anhydride, octenyl succinic anhydride, decenyl succinic anhydride, undecenyl succinic anhydride, dodecenyl succinic anhydride, tridecenyl succinic anhydride, hexadecenyl Alkenyl succinic anhydrides such as nil succinic anhydride and octadecenyl succinic anhydride can be preferably used.

  As the alkenyl succinic anhydride, each compound may be used alone, or two or more kinds may be used in combination.

  In the present specification, an alkenyl succinic anhydride having an olefin chain having a specific carbon number may be represented by combining the abbreviation (ASA) of alkenyl succinic anhydride and the carbon number of the olefin chain.

  For example, an alkenyl succinic anhydride having an olefin chain having 16 carbon atoms (hexadecenyl succinic anhydride) may be referred to as “ASA-C16”. The ASA used in the present invention may be described by a product name or a product code number. For example, AS1533 (manufactured by Seiko PMC Co., Ltd.), TNS135 (manufactured by Seiko PMC Co., Ltd.), Ricacid DDSA (tetrapropenyl succinic anhydride, manufactured by Shin Nihon Riken Co., Ltd.) and the like can be preferably used.

  The alkyl succinic anhydride is obtained by reducing the unsaturated bond of the alkenyl group of the alkenyl succinic anhydride represented by the formula (2) by hydrogenation (that is, a succinic acid having an alkenyl group converted to an alkyl group). Acid anhydrides) can be used.

  As these compounds, alkyl succinic anhydrides such as octyl succinic anhydride, dodecyl succinic anhydride, hexadecyl succinic anhydride, octadecyl succinic anhydride and the like can be preferably used.

  As the alkyl succinic anhydride, each compound may be used alone, or two or more kinds thereof may be used in combination. Moreover, an alkyl succinic anhydride and an alkenyl succinic anhydride can also be used together.

  The amount of the present anhydride required for chemical modification of lignocellulose fiber is preferably about 0.004 to 0.18 times mole, more preferably 0.04 to 0.18 times the number of moles of hydroxyl group contained in lignocellulose fiber (absolutely dry amount). About mole is preferable.

  The reaction between the lignocellulose fiber and the acid anhydride of formula (3) is preferably carried out in an organic solvent. Lignopulp fiber can be dried, suspended in an organic solvent and reacted with an acid anhydride of formula (3).

  Lignopulp fiber is usually in a hydrous state (aqueous dispersion). By performing an operation (solvent replacement operation) of adding an organic solvent to the lignopulp in the water-containing state, filtering, and dispersing and filtering again in the organic solvent, the reaction can be performed by dispersing the lignopulp in the organic solvent.

  The organic solvent used is preferably a water-soluble aprotic solvent that can swell lignopulp without reacting with the acid anhydride of formula (3). Examples of satisfying this condition include N-methylpyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMA), and tetrahydrofuran (THF).

  In the reaction between the lignocellulose fiber and the acid anhydride of formula (3), the reaction is preferably performed in the presence of a base in order to accelerate the reaction. As the base, amines such as pyridine and dimethylaniline, alkali metal salts of acetic acid such as potassium acetate and sodium acetate, and alkali metal carbonates such as lithium carbonate, potassium carbonate and sodium carbonate can be preferably used.

  The reaction temperature depends on the boiling point of the solvent used, but is preferably about 20 to 150 ° C, more preferably about 30 to 120 ° C, and further preferably about 40 to 100 ° C.

  The reaction time also depends on the type of acid anhydride of formula (3). The degree of half-esterification is obtained by collecting a part of lignocellulose fiber during the reaction, measuring the infrared (IR) absorption spectrum, and tracking the IR absorption peak based on the carbonyl stretching vibration of the half-ester generated by the reaction. It can be adjusted while checking the (substitution degree).

Degree of substitution in half esterification The degree to which the hydroxyl group present in lignopulp fiber was hearth-esterified (the degree of substitution in hearth esterification will be described.

  The half ester refers to an ester in a state where one carboxy group of dicarboxylic acid forms an ester bond with an alcoholic hydroxyl group, and one carboxy group is not ester-bonded (that is, a free carboxylic acid state). Therefore, the half esterification of lignocellulose means that an ester bond is formed with one carboxy group among the hydroxyl group and dicarboxylic acid in lignocellulose, and the other carboxy group is in a free state.

  In the half esterification reaction with the acid anhydride of formula (3), the hydrogen atom of the hydroxyl group in the lignocellulose fiber is substituted with one of the two carbonyl groups present in the acid anhydride of formula (3). A bond is formed and a half ester is formed.

  The half ester of lignocellulose is in a chemically bonded state in which the hydrogen atom of the hydroxyl group present in the lignocellulose is substituted by the carbonyl group in the carboxy group. In this specification, this is referred to as “lignocellulose by half esterification”. This is referred to as “substitution of a hydrogen atom for a hydroxyl group therein”.

  The degree of substitution (DS) is referred to as “degree of substitution of hydrogen atom of hydroxyl group in lignocellulose by half esterification (DS)”, “degree of half ester substitution (DS)” or “half esterification DS”. Defined as the average number of esterified hydroxyl groups in the repeating unit of cellulose.

  The repeating unit of pure cellulose is a glucopyranose residue (glucose residue), which has three hydroxyl groups. Accordingly, the upper limit of half-esterified DS of pure cellulose is 3.

  On the other hand, lignocellulose contains hemicellulose and lignin together with cellulose. The number of hydroxyl groups of the xylose residue in xylan and the galactose residue in arabinogalactan contained in hemicellulose is 2, and the number of hydroxyl groups of the lignin residue is 2, and these hydroxyl groups are less than 3. Therefore, the number of hydroxyl groups in the average repeating unit of lignocellulose is smaller than 3, and the upper limit is smaller than 3.

  From this, the upper limit of the half-esterified DS of lignocellulose fiber is smaller than 3. The upper limit of the half-esterified DS is about 2.7 to 2.8 depending on the contents of hemicellulose and lignin contained in the lignocellulose fiber.

  The half esterified DS of the present chemically modified lignocellulose fiber is preferably controlled to 0.01 to 0.4, more preferably 0.1 to 0.4. That is, the chemically modified lignocellulosic fiber as a raw material of the hot-press molded body is partially esterified with a carboxy group-containing acyl group represented by the above formula (1) in a part of the hydroxyl groups present in the lignocellulose. The substitution degree of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is preferably 0.1 to 0.4.

  If the half-esterified DS is less than 0.01, the plasticity tends to be insufficient at the time of hot-pressing processing, and molding tends to be difficult. When the half esterified DS exceeds 0.4, the viscosity of the reaction mixture increases and becomes a gel state, and it tends to be difficult to separate and wash the chemically modified lignocellulose fibers in the reaction mixture.

Chemical modification of lignocellulose fiber with carboxyalkyl group (Aspect (2))
As described in the aspect (2), in the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose fiber of the raw material has a part of hydroxyl groups present in the lignocellulose represented by the formula (2). Etherified with the represented carboxyalkyl group.

  The carboxyalkyl group represented by the above formula (2) is also referred to as “the present carboxyalkyl group”.

The lignocellulose fiber (chemically modified lignocellulose fiber) etherified with this carboxyalkyl group is converted to lignocellulose fiber using the following formula (4):
X- (CH ₂ ) _n -COOH (4)
(In the formula, n represents an integer of 1 to 3. X represents a halogen atom selected from the group consisting of Cl, Br and I.)
Is reacted with a halogenoalkyl carboxylic acid represented by the formula (hereinafter also referred to as “the present halogenoalkyl carboxylic acid”), and a part of the hydroxyl group present in the lignocellulose is carboxy represented by the above (2). By etherification with an alkyl group, the substitution degree of the hydrogen atom of the hydroxyl group in the lignocellulose to be etherified is set to 0.01 to 0.4, whereby the raw material (chemically modified lignocellulose fiber) of the present invention is produced. can do.

  The chemically modified lignocellulose fiber is reacted with a halogenoalkylcarboxylic acid or a salt thereof by heating in the presence of a base to form an ether bond between the oxygen atom of the hydroxyl group present in the lignocellulose and the present carboxyalkyl group. The formation of this ether bond is referred to herein as “the present etherification”, and this reaction is referred to as the “the present etherification reaction”.

  As this halogenoalkylcarboxylic acid, X (halogen atom) is preferably a chlorine atom or a bromine atom.

  The salt of the present halogenoalkylcarboxylic acid is preferably an alkali metal salt.

  Preferred halogenoalkyl carboxylic acids and salts thereof include chloroacetic acid, bromoacetic acid, 3-chloropropionic acid, 3-bromopropionic acid, 4-chlorobutyric acid and 4-bromobutyric acid, and their sodium, potassium and A lithium salt can be exemplified.

  Each of the present halogenoalkylcarboxylic acids and salts thereof may be used alone or in combination of two or more.

  The amount of the present halogenoalkylcarboxylic acid or salt thereof used in the present etherification reaction is usually preferably 0.01 to 0.45 times moles relative to the number of moles of hydroxyl groups contained in the lignocellulose fiber (absolutely dry amount), More preferably, the molar amount is 0.01 to 0.35 times.

  This etherification reaction can be performed in water or a mixed solvent of water and a water-soluble organic solvent (for example, alcohol). Lignocellulose fibers subjected to this reaction are usually produced as an aqueous suspension. It can be carried out by mixing the lignocellulose fiber with the base and the present halogenoalkylcarboxylic acid and / or salt thereof and heating them.

  As a base used in this reaction, hydroxide of alkali metal such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, Carbonates, hydrogen carbonates and the like can be suitably used.

  As for the usage-amount of a base, it is preferable to use normally about 1-5 equivalent with respect to this halogenoalkyl carboxylic acid, and it is more preferable to use about 1-4 equivalent.

  The etherification reaction is preferably performed at 30 to 90 ° C. with stirring.

  This reaction time is usually about 0.5 to 5 hours depending on the type and amount of the halogenoalkylcarboxylic acid or salt thereof used.

  A portion of lignocellulosic fiber during the reaction was sampled, the infrared (IR) absorption spectrum was measured, and the IR absorption peak based on the carbonyl stretching vibration of the carboxy group of the carboxyalkyl ether produced by the reaction was traced. It can be adjusted while confirming the degree of conversion (degree of substitution).

Degree of etherification The degree to which the hydroxyl group present in the lignopulp fiber was etherified with the present halogenoalkylcarboxylic acid will be described.

  In the etherification reaction of the present case, the hydrogen atom of the hydroxyl group in the lignocellulose fiber is substituted with the present carboxyalkyl group to form an ether bond. In the present specification, this is referred to as “degree of substitution of hydrogen atom of hydroxyl group in lignocellulose by etherification (DS)” or “degree of etherification substitution: etherification DS”. This represents the degree to which the hydroxyl group present in the lignopulp fiber was etherified with the present halogenoalkylcarboxylic acid.

  This degree of etherification substitution (etherified DS) is defined as the average number of etherified hydroxyl groups in the repeating unit of lignocellulose.

  The repeating unit of pure cellulose is a glucopyranose residue (glucose residue), which has three hydroxyl groups. Therefore, the upper limit of DS for etherification of pure cellulose is 3.

  On the other hand, lignocellulose contains hemicellulose and lignin together with cellulose. The number of hydroxyl groups of the xylose residue in xylan and the galactose residue in arabinogalactan contained in hemicellulose is 2, and the number of hydroxyl groups of the lignin residue is 2, and these hydroxyl groups are less than 3. Therefore, the number of hydroxyl groups in the average repeating unit of lignocellulose is smaller than 3, and the upper limit is smaller than 3.

  From this, the upper limit value of etherified DS of lignocellulose fiber is smaller than 3, similar to the half esterified DS, and the upper limit value depends on the content of hemicellulose and lignin contained in the lignocellulose fiber. 2.7 to 2.8.

  The etherification DS of the present chemically modified lignocellulose fiber is preferably controlled to 0.01 to 0.4, more preferably 0.01 to 0.3, and still more preferably 0.01 to 0.2. That is, in the chemically modified lignocellulose fiber of the hot-press molded body, a part of the hydroxyl groups present in the lignocellulose are etherified with the carboxyalkyl group represented by the above formula (2), and the etherified The degree of substitution of the hydrogen atom of the hydroxyl group in lignocellulose is preferably 0.01 to 0.4.

  If the etherified DS is less than 0.01, the plasticity tends to be insufficient during hot pressing, making molding difficult. When the etherification DS exceeds 0.4, the viscosity of the reaction mixture increases and becomes a gel state, and it tends to be difficult to separate and wash the chemically modified lignocellulose fibers in the reaction mixture.

  The lignocellulosic fiber is neutralized after the half esterification with the acid anhydride of the formula (3) or after the etherification reaction with the halogenoalkylcarboxylic acid of the formula (4). Then, the chemically modified lignocellulosic fibers are separated and washed by a liquid removal device such as filtration or centrifugation.

  For the cleaning, water or a solvent such as alcohol can be used if necessary.

  After washing, the chemically modified lignocellulose fiber is subjected to the next hot pressing process.

Hot-pressed body (Inventions 2 and 3)
The following aspect (1) or (2) is a preferable aspect of the hot-press molded body of the present invention.

Aspect (1)
In the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose fiber has the following properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.1 to 0.4.

Aspect (2)
In the hot-pressed product of chemically modified lignocellulose, the chemically modified lignocellulose fiber has the following properties (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.3.

The carboxyalkyl group represented by the formula (2) is preferably a carboxymethyl group (—CH ₂ —COOH).

Lignin component content (Inventions 4 and 10)
In the hot-press molded body of the present invention, the lignin component content of the chemically modified lignocellulose fiber is preferably about 2 to 40% by mass. The lignin component content of the chemically modified lignocellulose fiber is more preferably about 2 to 35% by mass, and further preferably about 2 to 30% by mass.

  The lignin component content means the mass% of the lignin component in the mass (the mass in terms of lignocellulose) obtained by removing the mass of the chemically modified group from the chemically modified lignocellulose. Lignin is not usually removed from the raw lignocellulose by chemical modification, or a small amount even if it is removed. The lignin component content (% by mass) corresponds to the lignin-containing mass% contained in the lignocellulose used for this chemical modification.

  The hot-press molded body of the present invention also includes a combination of the above aspects (1) and (2). That is, a mixture of lignocellulose in which part of the hydroxyl groups present in lignocellulose with the acyl group of formula (1) is half-esterified and lignocellulose etherified with the carboxyalkyl group of formula (2) The hot-press molded body comprising the above-mentioned is included in the hot-press molded body of the chemically modified lignocellulose of the present invention.

(2) Manufacturing method of hot-pressed product of chemically modified lignocellulose
Manufacturing method of hot-pressed body (Invention 6-8)
The method for producing a hot-pressed product of chemically modified lignocellulose of the present invention includes a step of compressing a fiber assembly composed of chemically modified lignocellulose fibers under heating, wherein the chemically modified lignocellulose comprises the following (a) and (b ) Characteristics:
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4.

The carboxyalkyl group represented by the formula (2) is preferably a carboxymethyl group (—CH ₂ —COOH).

  In the method for producing a hot-pressed product, the chemically modified lignocellulose fiber is partially esterified with a carboxyl group-containing acyl group represented by the formula (1), wherein a part of the hydroxyl groups present in the lignocellulose are formed. The substitution degree of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is preferably 0.1 to 0.4.

  In the method for producing a hot-press molded body, the chemically modified lignocellulose fiber is obtained by etherifying a part of the hydroxyl groups present in the lignocellulose with a carboxyalkyl group represented by the formula (2). It is preferable that the substitution degree of the hydrogen atom of the hydroxyl group in the converted lignocellulose is 0.01 to 0.3.

  The chemically modified lignocellulosic fiber or fiber aggregate is preferably subjected to compression molding under heating after being washed or / and dispersed as required. A uniform molding surface can be obtained before molding.

  As one method of pulverization, for example, ethanol or the like, preferably a solvent having a boiling point of 100 ° C. or less, is added to a fiber or a fiber assembly containing chemically modified lignocellulose, and the mixture is stirred with a mixer or the like to obtain a solid content (chemical modification). It is preferable to obtain a suspension in which the concentration of (fiber lignocellulose fiber) is adjusted. Next, it is preferable to obtain a molding material (fiber aggregate of chemically modified lignocellulose fibers) by removing the solvent from the suspension by means such as filtration and drying.

  The fiber assembly of chemically modified lignocellulosic fibers tends to shrink due to drying, and the pressure surface tends to be curved. As described above, when the molding material (fiber assembly of chemically modified lignocellulosic fibers) is prepared by filtration, a filtration surface having the same shape as the bottom surface of the mold (molding die) of the target molded body It is preferable that a material for molding is prepared by filtering with a filter having the following, and then this is placed in a mold and hot-pressure molded. Thereby, the molded object which has a uniform surface and is excellent in an intensity | strength characteristic can be manufactured.

Heating temperature and compression pressure (Invention 11)
In producing a hot-pressed product of chemically modified lignocellulose, the temperature of the hot pressing is preferably about 160 to 240 ° C. in order to avoid thermal decomposition of the chemically modified lignocellulose fiber.

  The compressing pressure at the time of hot pressing is preferably set to 30 MPa to 100 MPa.

  In the method for producing a hot-pressed product of chemically modified lignocellulose according to the present invention, the fiber assembly comprising the chemically modified lignocellulose fiber is compressed at a pressure of 30 MPa to 100 MPa while being heated at a temperature of 160 to 240 ° C. Is preferred. Chemically modified lignocellulose exhibits plasticity and avoids thermal degradation. By processing a fiber assembly of chemically modified lignocellulosic fibers at these temperatures and pressures, a hot-press molded product having excellent strength characteristics can be produced.

Method for producing a hot-pressed body including the first step and the second step (Inventions 13 and 14)
When the production method of the hot-pressed product of the present invention is described in the order of steps from the chemical modification step of lignocellulose fiber, the production method of the hot-pressed product of the chemically modified lignocellulose of the present invention includes the following first step and second step. It is preferable to contain.

(1) First step :
(A-1) In lignocellulose fiber, the following formula (3):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
A part of the hydroxyl group present in the lignocellulose is reacted with a succinic anhydride or a derivative thereof represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
By half-esterification with a carboxy group-containing acyl group represented by
The step of producing a chemically modified lignocellulose fiber by setting the substitution degree of the hydrogen atom of the hydroxyl group in the lignocellulose to be half-esterified to 0.01 to 0.4,
Or
(A-2) In lignocellulose fiber, the following formula (4):
X- (CH ₂ ) _n -COOH (4)
(In the formula, n represents an integer of 1 to 3. X represents a halogen atom selected from the group consisting of Cl, Br and I.)
Is reacted with a halogenoalkyl carboxylic acid represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
By etherification with a carboxyalkyl group represented by
The step of producing chemically modified lignocellulose fibers by setting the degree of substitution of hydrogen atoms of hydroxyl groups in the lignocellulose to be etherified to 0.01 to 0.4,
(2) Second step :
A step of compressing the fiber assembly made of the chemically modified lignocellulose fiber obtained in the first step under heating.

The carboxyalkyl group represented by the formula (2) is preferably a carboxymethyl group (—CH ₂ —COOH).

  In the method for producing a hot-press molded body, it is preferable that the temperature of heating the fiber assembly composed of the chemically modified lignocellulose fiber is 160 to 240 ° C. and the pressure to be compressed is 30 to 100 MPa.

  Among the chemically modified lignocellulose hot-press molded articles of the present invention, as one embodiment, lignocellulose in which a part of the hydroxyl groups present in the lignocellulose with the acyl group of the formula (1) is half-esterified and the above formula ( There is a hot-pressed product made of a mixture of lignocellulose etherified with a carboxyalkyl group of 2). In this embodiment, the lignocellulose fiber in which a part of the hydroxyl group present in the lignocellulose is half-esterified with the acyl group of the formula (1) obtained in the first step and the carboxyalkyl group of the formula (2) It can be produced by mixing with etherified lignocellulose fibers and compressing this mixed fiber aggregate under heating.

(3) Hot-pressed compact of chemically modified lignocellulose
Hot-pressed product further containing a thermoplastic resin (Inventions 5 and 12)
In the hot-press molded body of the present invention, it is preferable that the chemically modified lignocellulose fiber further contains a thermoplastic resin.

  In the method for producing a hot-pressed product of the present invention, it is preferable to use a fiber assembly further containing a thermoplastic resin as the fiber assembly composed of the chemically modified lignocellulose fibers.

  The hot-press molded body of the present invention may appropriately contain a resin as long as the effects of the present invention are not impaired, and it is preferable to use a thermoplastic resin among the resins.

  As a thermoplastic resin, polyamide (nylon resin, PA), polyacetal (POM), polyolefin resin [polypropylene (PP), maleic anhydride-modified PP (in terms of mechanical properties, heat resistance, surface smoothness and appearance) MAPP), polyethylene (PE), etc.], polyester, polycarbonate, polylactic acid, polyester, polylactic acid and polyester copolymer resin, PBS resin (polybutylene succinate), polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin) Etc. are preferably used.

  Polyvinyl chloride, polyvinylidene chloride, fluororesin, (meth) acrylic resin, polyphenylene oxide, (thermoplastic) polyurethane, vinyl ether resin, polysulfone resin, cellulose resin (for example, triacetylated cellulose, diacetylated cellulose) Etc. can also be preferably used.

  Nylon 66 (polyhexamethylene adipamide, polyamide 66, PA66), nylon 6 (ε-caprolactam ring-opening polymer, polyamide 6, PA6), nylon 11 (undecanlactam) as polyamide (amide resin) Polycondensed polyamide, polyamide 11, PA11), nylon 12 (polyamide with ring-opening polycondensation of lauryl lactam, polyamide 12, PA12), nylon 46 (polyamide 46, PA46), nylon 610 (polyamide 610, PA610), nylon 612 It is preferable to use an aliphatic amide resin such as (polyamide 612, PA612). As the polyamide resin, it is also preferable to use an aromatic polyamide such as an aromatic diamine such as phenylenediamine and an aromatic dicarboxylic acid such as terephthaloyl chloride or isophthaloyl chloride or a derivative thereof.

  These resins may be used alone or as a mixed resin of two or more.

  Since the polyamide resin (PA) has a highly polar amide bond in the molecular structure, it has an advantage of high affinity with the cellulosic material. As the polyamide resin (PA), it is preferable to use PA6, PA66, PA11, PA12 or the like, a polyamide copolymer resin, or the like.

  As polyacetal (POM), polymers and copolymers such as trioxane, formaldehyde, ethylene oxide can be preferably used.

  As the polyolefin resin, it is preferable to use general-purpose polypropylene (PP), polyethylene (PE, particularly high-density polyethylene: HDPE) or the like as a structural member. In addition, it is preferable to use maleic anhydride-modified polypropylene (MAPP) that is highly compatible with these versatile polyolefins.

  As polyester, aromatic polyester, aliphatic polyester, unsaturated polyester, etc. can be used preferably.

  As the aromatic polyester, a copolymer of a diol such as ethylene glycol, propylene glycol, or 1,4-butanediol and an aromatic dicarboxylic acid such as terephthalic acid can be preferably used.

  Aliphatic polyesters include polymers and copolymers of diols and aliphatic dicarboxylic acids such as succinic acid and valeric acid, homopolymers or copolymers of hydroxycarboxylic acids such as glycolic acid and lactic acid, diols, An aliphatic dicarboxylic acid and a copolymer of the hydroxycarboxylic acid can be preferably used.

  As the unsaturated polyester, a diol, an unsaturated dicarboxylic acid such as maleic anhydride, and a copolymer with a vinyl monomer such as styrene as required can be preferably used.

  When the hot-press molded product of the present invention contains the thermoplastic resin, the chemically modified lignocellulose fiber that is a raw material and the thermoplastic resin are mixed, and the mixture of the fiber and the thermoplastic resin is heated under the above conditions. It can be manufactured by pressure forming.

  The mixture of chemically modified lignocellulosic fibers and thermoplastic resin can be prepared by separating the resin into chemically modified lignocellulose fibers in which the resin is dispersed in an insoluble solvent, and using a separation means such as filtration or centrifugation. it can.

  Mixing of chemically modified lignocellulose fiber and thermoplastic resin can be performed quickly by mixing the resin into the dispersion liquid (aqueous dispersion) of chemically modified lignocellulose fiber after chemical modification and filtering it. A lignocellulose fiber and resin mixture can be prepared.

  It is preferable to mix the resin in the form of fine fibers, fine powder, or particles in order to obtain hot press molding in which chemically modified lignocellulose and the resin are uniformly mixed.

Other Additives to the Hot-Pressed Molded Body The hot-pressed molded body of the present invention is an inorganic compound such as zeolite, ceramics, and metal powder, a colorant, a conductive agent, and an antistatic agent as long as the effects of the present invention are not impaired. Further, an antioxidant and the like can be appropriately contained. These additives can be mixed with a raw material for producing a hot-press molded body (chemically modified lignocellulose fiber aggregate) to produce the hot-press molded body of the present invention.

Salt of Hot-Pressed Molded Body The hot-pressed molded body of the present invention is a carboxy group in the carboxy-containing acyl group represented by the above formula (1) and the above formula (2), as long as the effects of the present invention are not impaired. A part or all of the carboxy group in the carboxyalkyl group-containing acyl group represented by) may form a salt, and such a hot-pressed product is also included in the present invention.

  Examples of such salts include alkali metal salts, alkaline earth metal salts, and organic salts with amines.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

  The present invention is not limited to these examples.

  In Examples and Comparisons,% of component content of lignin, cellulose, hemicellulose and the like in pulp, lignocellulose, and modified lignocellulose indicates mass% unless otherwise specified.

  Unless otherwise specified,% of the concentration of each component in the dispersion or solution indicates mass%.

  In the examples and production examples (raw material production), “chemical modification” or “modification” may be used as a term in place of “chemical modification” or “modification”.

  “Native” may be used as a term in place of “not chemically modified”, “unchemically modified” or “unmodified”.

1． Terms / abbreviations The following abbreviations used in Examples and Comparative Examples have the following meanings.

NCTMP: Chemical thermomechanical pulp derived from conifers
NUKP: Unbleached kraft pulp derived from conifers
CSF: Canadian standard freeness
MCA: Monochloroacetic acid

2． Raw materials used
2-1. Chemical thermomechanical pulp (NCTMP) derived from conifers
Composition (% by mass):
Lignin 27

2-2. Unbleached kraft pulp derived from conifers (NUKP)
Composition (% by mass):
Cellulose (Cel) 74.5,
Lignin (Lig) 9.9,
Hemicellulose (Hemcel) 15.6 [Glucomannan (GlcMan) 7.3, Xylan (Xy) 7.4, Arabinogalactan (AraGal) 0.9 (Arabinan (Ara) 0.45, Galactan (Gal) 0.45)]

3． Test method / measurement method and equipment used
(I) Lignin determination method (Klarson method)
Glass fiber filter paper (GA55) was dried in an oven at 105 ° C. until it reached a constant weight, allowed to cool in a desiccator, and then weighed. Lignocellulose (sample of about 0.2 g) that had been completely dried at 105 ° C. was precisely weighed and placed in a 50 mL beaker. 3 mL of 72% concentrated sulfuric acid was added, and the mixture was left in warm water at 30 ° C. for 1 hour while being appropriately crushed with a glass rod so that the contents were uniform.

  Next, 84 g of distilled water was added to the contents, and quantitatively transferred to an Erlenmeyer flask, followed by reaction at 120 ° C. for 1 hour in an autoclave. After standing to cool, the contents were filtered through a glass fiber filter paper and washed with 200 mL of distilled water. Dry and weigh until constant weight in 105 ° C oven.

(Ii) Determination method of cellulose and hemicellulose (sugar analysis)
Lignocellulose was placed in an oven desiccator and dried at 50 ° C. for 3 hours while reducing the pressure with a vacuum pump. About 30 mg of the dried sample was precisely weighed and placed in a pressure test tube, and then 200 μL of fucose (0.1 g / mL) was added as an internal standard. Using a pipette, 0.3 mL of 72% concentrated sulfuric acid was added, and the mixture was pushed evenly with a glass rod and reacted in a water bath at 30 ° C. for 1 hour.

  After 1 hour, 8.4 mL of distilled water was added, and the mixture was reacted in an autoclave at 120 ° C. for 1 hour. After allowing to cool, ultrapure water was added and diluted appropriately. The diluted solution was subjected to ion chromatographic analysis manufactured by Thermo Fisher Scientific, and the sugar component contained in the sample was analyzed.

(Iii) Measurement of average fiber diameter of lignocellulose fiber A water suspension of lignocellulose was dispersed in ethanol, and water was removed together with ethanol by filtration. The ethanol residue of the obtained filtration residue was dried under reduced pressure at room temperature. About this dried lignocellulose, the scanning electron microscope (SEM) photograph of 500-10,000 times was image | photographed, the fiber diameter of at least 50 or more was measured on the photographed photo, and the average value was computed.

(Iv) Strength test of hot-pressed molded body A hot-pressed molded body having a thickness of 1 mm was cut into a length of 30 mm and a width of 5 mm using a cutter to obtain a sample. This sample was subjected to a three-point bending test at a distance between supporting points of 20 mm and a bending speed of 5 mm / min using a universal testing machine (model 3365 twin column tabletop testing system manufactured by Instron).

Four. Production Example Production of lignocellulosic fiber (raw material for hot-pressed products of Examples and Comparative Examples)
Production Example 1
Ref-NCTMP (defibration by NCFMP refiner)
Water was added to the NCTMP (lignin content: 27% by mass) to prepare a pulp slurry having a solid content concentration of 3.0% by mass. The pulp slurry was defibrated using a refiner (Lab Refiner Model SDR14, manufactured by Aikawa Tekko Co., Ltd.) under the following conditions.

Defibration condition processing amount: 30L
Flow rate: 600mL / min
Temperature: 40-60 ° C
Time: about 10min
The obtained lignocellulose fiber is called Ref-NCTMP.

  CSF was 60 mL.

  Table 1 shows the average fiber diameter of Ref-NCTMP.

Production Example 2
BM-NCTMP (defibration with NCTMP bead mill)
Water was added to the NCTMP (lignin content: 27% by mass) to prepare a pulp slurry having a solid content concentration of 0.75% by mass. This pulp slurry was defibrated three times under the following conditions using a bead mill (model NVM-2 manufactured by Imex Corporation).

Defibration condition beads: Zirconia beads (diameter: 1mm)
Bead filling rate: 70%
Rotation speed: 2,000rpm
Discharge rate: 600mL / min
The obtained lignocellulose fiber is called BM-NCTMP.

Production Example 3
Ref-NUKP (defibration with NUKP refiner)
Lignocellulose fibers were obtained in the same manner as in Production Example 1, except that the raw material was changed to the NUKP (lignin content: 9.9% by mass).

  The obtained lignocellulose fiber is called Ref-NUKP.

The average fiber diameter of Ref-NUKP is shown in Table 1.
CSF was 50 mL.

Production Example 4
Unbleached kraft pulp (BM-NUKP) derived from conifers defibrated by a bead mill
Lignocellulose fibers were obtained in the same manner as in Production Example 2, except that the raw material was changed to unbleached kraft pulp derived from conifers (NUKP, lignin content: 9.9% by mass).

  The obtained lignocellulose fiber is called BM-NUKP.

  Table 1 shows the average fiber diameter of BM-NUKP.

  Table 1 summarizes the amount of lignin and the average fiber diameter of the lignocellulose fibers obtained in the production examples.

Five. Example
Example 1: Preparation of CM (BM-NUKP) and its hot-pressed body
Preparation of chemically modified lignocellulose 20g of lignocellulose fiber (BM-NUKP) obtained in Production Example 4 above in solid content, 20g of water, 160g of water, 480g of isopropanol (IPA), 2.6g of sodium hydroxide in a 1L three-necked flask Were mixed and stirred at room temperature for 30 minutes. Subsequently, 2.4 g of monochloroacetic acid was added, and the mixture was further stirred for 30 minutes.

  Then, raise the internal temperature of the flask to 70 ° C., hold for 3 hours, and carboxymethylated (CM) lignocellulose fiber [this chemically modified lignocellulose fiber, CM (BM-NUKP) as chemically modified lignocellulose fiber Call it. The sodium salt was obtained.

  After cooling, neutralize with 2N hydrochloric acid aqueous solution, take out the reaction mixture, remove the solvent and water-soluble residual components by filtration, dilute again with water, and repeat filtration to wash the fiber aggregate of CM (BM-NUKP) did.

  The CM substitution degree (DS) of the obtained CM (BM-NUKP) was 0.04.

  DS has the meaning as described in the above-mentioned section “DETAILED DESCRIPTION”.

  The method of obtaining the substitution degree (DS) for commercialization is shown below.

  DS is the number of carboxymethyl groups added per repeating unit.

  The anionic ion equivalent (anionic group amount per weight) increased by modification is expressed as follows using this DS (α) and the apparent formula amount (B) per repeating unit of unmodified lignocellulose. I can express.

A−A ₀ = α × 10 ³ / (B + 58 × α)
α: Monochloroacetic acid addition rate (DS)
A: Anionic ion equivalent of CM lignocellulose [meq / g]
A ₀ : Anionic ion equivalent of unmodified lignocellulose [meq / g]
B: Apparent formula amount of unmodified lignocellulose By arranging this formula with respect to α, DS (α) can be obtained by the following formula.

α = B × (A−A ₀ ) / {1,000−58 × (A−A ₀ )}
The anionic ion equivalent (A or A ₀ ) was calculated by the nitric acid methanol method.

  The CMized or unmodified lignocellulose-containing slurry was weighed so that the weight of the dried product was about 2 g, and placed in a 300 mL stoppered Erlenmeyer flask. In this 300 mL stoppered Erlenmeyer flask, 100 mL of methanol nitrate (a solution obtained by adding 100 mL of special grade concentrated nitric acid to 1 liter of anhydrous methanol) was added, and the contents of the 300 mL stoppered Erlenmeyer flask were shaken for 3 hours to obtain a pulp slurry.

  After removing the pulp slurry, in order to remove the remaining water-soluble chemicals, the filtration residue is put into a 300 mL glass container, and 100 mL of 80% methanol (a mixture of 80 g of anhydrous methanol and 20 g of water) is added and stirred. The operation of filtering again was repeated 3 times. 80% methanol was added to the obtained filtration residue to wet it, 100 mL of 0.1N sodium hydroxide aqueous solution was added, and the mixture was stirred at room temperature for 3 hours to obtain a pulp slurry.

  To this pulp slurry, an excess amount of sodium hydroxide was titrated with 0.1N sulfuric acid using phenolphthalein as an indicator.

  The anionic ion equivalent was calculated by the following formula.

Anionic ion equivalent of CMized or unmodified lignocellulose = (F ₁ -F ₂ ) × 0.1 / W
F ₁ : 0.1N sodium hydroxide addition amount [mL]
F ₂ : 0.1N sulfuric acid titration [mL]
The apparent formula amount (B) of unmodified lignocellulose was calculated by the following formula.

B = {196 × L _m + 162 × (100−L _m )} / 100
L _m : molar ratio of lignin contained in unmodified lignocellulose [mol%]
The molar ratio (L _m ) of lignin contained in unmodified lignocellulose was calculated by the following formula.

L _m = (L _w / 196) / {(L _w / 196) + (100−L _w ) / 162} × 100
L _w : Weight ratio of lignin contained in unmodified lignocellulose [wt%]
The weight ratio (L _w ) of lignin contained in unmodified lignocellulose was measured by the Klarson method.

The glass fiber filter paper (GA55) was dried to a constant weight in a 105 ° C. oven, allowed to cool in a desiccator, and then weighed (W _F ). Lignocellulose (approximately 0.2g of sample) dried to constant weight in an oven at 105 ° C is weighed precisely (W ₀ ), added with 3mL of 72% sulfuric acid, and crushed appropriately with a glass rod to make the contents uniform. And kept in a 30 ° C. water bath for 1 hour.

  Next, 84 g of distilled water was added to the contents, and the mixture was kept at 120 ° C. for 1 hour in an autoclave. After standing to cool, the contents were filtered with glass fiber filter paper and washed with 200 mL of distilled water.

The obtained filtration residue and glass fiber filter paper are dried in a 105 ° C oven to a constant weight, weighed (W _total ), and the weight of the fiber glass filter paper (W _F ) is subtracted to calculate the pulp weight after lignin removal (W ₁ = W _total -W _F ).

The weight ratio (L _w ) of lignin contained in unmodified lignocellulose was calculated by the following formula.

L _w = (W ₀ −W ₁ ) / W ₀ × 100
In addition, the formula amount of unmodified lignocellulose (calculated in consideration of the mole fractions of cellulose, lignin and hemicellulose in lignocellulose) is usually used for the calculation of DS. As described above, there is almost no error even if DS is calculated using the apparent formula amount (B) calculated using only the molar fraction of cellulose and lignin instead of the formula amount of lignocellulose. Five%). In the present invention, DS was calculated by the above formula.

Hot-press molding of chemically modified lignocellulose The CM (BM-NUKP) fiber assembly described above is dried and sealed in a mold, heated to 200 ° C and pressurized to 100 MPa for 3 minutes to maintain thickness. A hot-pressed product of 1 mm thick chemically modified lignocellulose [CM (BM-NUKP)] was obtained.

  The obtained hot-pressed product was cut into a length of 30 mm and a width of 5 mm using a cutter to obtain a sample. This sample was subjected to a three-point bending test using a universal testing machine (model 3365 type twin column tabletop testing system manufactured by Instron) at a distance between supporting points of 20 mm and a bending speed of 5 mm / min.

  As a result, the sample had a bending strength of 217 MPa and a bending elastic modulus of 10.7 GPa.

  Tables 2 and 3 summarize the production conditions of the above-mentioned CM lignocellulosic fibers, the production conditions of the above-mentioned CM lignocellulosic modified molded article, and the physical property measurement results, respectively.

Example 2
A CM-shaped lignocellulose hot-press molded body was obtained in the same manner as in Example 1 except that the pressing condition in the hot-press molding was changed to 30 MPa. As a result of the bending test of the hot-pressed product, the bending strength was 207 MPa and the bending elastic modulus was 9.7 GPa.

  Tables 2 and 3 summarize the production conditions of the above-mentioned CM lignocellulosic fiber, the production conditions of the above-mentioned CM lignocellulose-modified molded product, and the physical property measurement results, respectively.

Examples 3-6
Except for changing the amount of lignocellulose and the reagent to be added to the amount shown in Table 2, CM-converted lignocellulose fiber was obtained in the same manner as in Example 1, and then this was changed to CM-converted lignocellulose under the production conditions shown in Table 3. A hot-pressed product was obtained.

  Table 2 shows the physical properties of the obtained CM lignocellulose fibers. Table 3 shows the physical properties of CM-formed lignocellulose hot-pressed products. The density of the hot-pressed product was also measured and listed in Table 3.

In the table, the meanings of the following abbreviations are as follows.
CM: Carboxymethylation
AS: Alkenyl succinic acid half esterification
BM: Defibered with a bead mill
Ref: Disassembling with refiner
NUKP: Unbleached kraft pulp derived from conifers
NCTMP: Chemical thermomechanical pulp derived from conifers.

Therefore, CM (BM-NUKP) means chemically modified lignocellulose fibers obtained by defibrating unbleached kraft pulp derived from coniferous trees with a bead mill to obtain lignocellulose fibers and carboxymethylating them.

Example 7: Preparation of AS (BM-NUKP) and its hot-pressed body
Preparation of chemically modified (AS modified) lignocellulose fibers
A 1-L three-necked flask was charged with 20 g of the lignocellulose (BM-NUKP) fiber obtained in Production Example 4 above in solids and 650 g of N-methylpyrrolidone (NMP), and dehydrated under reduced pressure at 80 ° C. with stirring. .

  Subsequently, nitrogen was introduced to return to normal pressure, alkenyl succinic anhydride (T-NS135, produced by Hoshimitsu PMC Co., Ltd., 16 carbon atoms other than succinic anhydride was added) 5.6 g, potassium carbonate 1.2 g was added, This was kept for 3 hours to obtain a potassium salt of AS-modified lignocellulose (referred to as AS (BM-NUKP)) as a chemically-modified lignocellulose fiber.

  After cooling, the reaction mixture was neutralized by putting it in a 2N aqueous hydrochloric acid solution, and the solvent and water-soluble residual components were removed by filtration. Further, the fiber assembly of chemically modified lignocellulose [AS (BM-NUKP)] was obtained by sequentially repeating dilution and filtration with acetone, ethanol, and water.

  The degree of substitution (DS) of the obtained chemically modified lignocellulose [AS (BM-NUKP)] was 0.13.

  The production conditions and physical properties of chemically modified (AS) lignocellulose are summarized in Table 4.

  DS has the same meaning as described in the above-mentioned section [Detailed Description of the Invention].

  The following shows how to obtain the AS DS.

  DS is the number of ASAs added per repeating unit.

  The addition equivalent of ASA (addition amount of ASA per weight of the modified lignocellulose) is this DS (α), the molecular weight of ASA (M), the apparent formula weight per repeating unit of unmodified lignocellulose (B) Can be expressed as follows.

A = α × 10 ³ / (B + M × α)
α: ASA addition rate (DS)
A: Additional equivalent of ASA [meq / g]
B: Apparent formula amount of unmodified lignocellulose By arranging this formula with respect to α, DS (α) can be obtained by the following formula.

α = B × A / {1,000−M × A}
The additional equivalent of ASA was measured and calculated by the following method.

  The ASA-added lignocellulose-containing slurry was weighed so that the weight of the dried product was about 0.5 g and placed in a 100 mL beaker. Ethanol 15mL and water 5mL were added here, and it stirred at room temperature for 30 minutes, and obtained the pulp slurry. Subsequently, 10 mL of 0.5N sodium hydroxide solution was added and stirred at 70 ° C. for 15 minutes, then cooled to room temperature and further stirred overnight.

  To the resulting mixture, an excess amount of sodium hydroxide was titrated with 0.1N aqueous hydrochloric acid using phenolphthalein as an indicator.

  The additional equivalent of ASA was calculated by the following formula.

ASA additional equivalent = (F ₁ × 0.5-F ₂ × 0.1-A ₀ × W) / 2 / W
F ₁ : Amount of 0.5N sodium hydroxide added [mL]
F ₂ : 0.1N hydrochloric acid titration [mL]
W: Dry weight [g] of weighed ASA-added or unmodified lignocellulose
A ₀ : Anionic ion equivalent of unmodified lignocellulose [meq / g]
The apparent formula amount (B) of unmodified lignocellulose was calculated by the method described above.

Hot-press molding of chemically modified (AS-modified) lignocellulose The above-mentioned chemically modified lignocellulose [AS (BM-NUKP)] fiber assembly was dried and sealed in a mold, then heated to 200 ° C and 100 MPa By holding for 3 minutes in a pressurized state, a hot-pressed product (Example 7) of chemically modified (AS-modified) lignocellulose [AS (BM-NUKP)] was obtained.

  The obtained hot-pressed product was cut into a length of 30 mm and a width of 5 mm using a cutter to obtain a sample. This sample was subjected to a three-point bending test using a universal testing machine (model 3365 type twin column tabletop testing system manufactured by Instron) at a distance between supporting points of 20 mm and a bending speed of 5 mm / min.

  As a result, the hot-pressed product had a bending strength of 197 MPa and a bending elastic modulus of 10.2 GPa.

  The results are summarized in Table 5.

Examples 8-13
The lignocellulosic fiber (the raw material of chemically modified fiber) was changed and chemically modified under the conditions shown in Table 4 to obtain AS-modified lignocellulose fiber. Next, the solvent in which the AS-modified lignocellulose fiber aggregate was dispersed was changed to obtain a fiber aggregate. This was processed under the shape and hot press conditions shown in Table 5 to obtain hot press molded bodies of Examples 8 to 13.

  The results of the bending test measured in the same manner as in Example 7 are also shown in Table 5.

  The density of the hot-pressed product was also measured and listed in Table 5.

Comparative Example 1
The lignocellulosic fiber wet product obtained in Production Example 2 was repeatedly diluted with ethanol and filtered to obtain an aggregate of lignocellulose fibers.

  The obtained fiber assembly is dried and sealed in a mold, heated to 200 ° C. and kept at 50 MPa for 3 minutes to obtain a fiber assembly of unmodified lignocellulose having a thickness of 1 mm. It was.

  The obtained lignocellulose fiber aggregate was cut into a length of 30 mm and a width of 5 mm using a cutter to obtain a sample. This sample was subjected to a three-point bending test using a universal testing machine (model 3365 type twin column tabletop testing system manufactured by Instron) at a distance between supporting points of 20 mm and a bending speed of 5 mm / min.

As a result, the obtained lignocellulose fiber assembly had a bending strength of 166 MPa and a bending elastic modulus of 7.3 GPa. The density was 1.30 g / cm ³ .

  Table 6 summarizes the physical properties of the above lignocellulose fibers, and Table 7 summarizes the production conditions and physical property measurement results of the lignocellulose fiber aggregates.

Comparative Examples 2 and 3
A lignocellulose fiber aggregate was obtained in the same manner as in Comparative Example 1, except that the production conditions of the lignocellulose fiber and the hot-press molded body were changed as shown in Tables 6 and 7.

  The physical property measurement results of the obtained lignocellulose fiber aggregate are summarized in Table 7.

It summarizes the test results of Examples and Comparative Examples are summarized in Table 8 of the Examples and Comparative Examples.

Discussion The reason why the hot-press molded product of the present invention showing the excellent effect by hot-pressing chemically modified lignocellulose fiber is considered as follows.

  The hot-press molded body of the present invention has a structure in which (i) lignin, chemically modified lignin, hemicellulose, and chemically modified hemicellulose contained in the chemically modified lignocellulosic fiber as a matrix are (ii) It can also be said to be a nanocomposite using cellulose nanofiber (CNF) and chemically modified cellulose as a filler.

  Usually, in the design of nanocomposites, the thermoplasticity of the matrix component, the uniform dispersion of the filler in the matrix component, and the affinity between the matrix component and the filler are important. In the present invention, chemical modification of hydroxyl groups of lignin and hemicellulose functions effectively in order to make the thermoplasticity of the matrix component suitable. Although lignin shows thermoplasticity even in an unmodified state, it is considered that the chemical modification improved the thermoplasticity by inhibiting the mutual bonding of the lignins with the functional group.

  Hemicellulose is usually bonded to each other by hydrogen bonding with a hydroxyl group, and exhibits almost no thermoplasticity. In the present invention, it is considered that the thermoplasticity of hemicellulose is also improved by inhibiting this hydrogen bond by chemical modification.

  It is considered that chemical modification of the hydroxyl group of hemicellulose also functions effectively for uniform dispersion of the filler in the matrix component. In the unmodified state, hemicellulose plays a role of bundling CNF, but it is considered that CNF was released from the bundled state due to the improved thermoplasticity of hemicellulose as described above.

  In woody materials, the affinity of matrix components and fillers is maintained by bundling hemicelluloses of multiple CNFs and solidifying the aggregates with lignin as an adhesive. In the present invention, since the degree of chemical modification is appropriately controlled, it is considered that this naturally occurring function is suppressed to such an extent that it is not impaired.

These effects are combined to act synergistically, and the effect of the present invention is obtained.
The reason why the functional groups shown in Formula (1) and Formula (2) are superior as functional groups to be introduced by chemical modification is that hydrogen bond inhibition, lignin interaction inhibition, lignin, hemicellulose, CNF This is considered to be because the balance was excellent, such as not compromising the affinity.

Claims (14)

A hot-pressed product of chemically modified lignocellulose,
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

(In the formula, R ¹ and R ² each represent a hydrogen atom, a methyl group, an ethyl group, or a C 3-20 alkenyl group or alkyl group which may have a branched chain, provided that R ¹ and R ² When one of these has 4 to 20 carbon atoms, either R ¹ or R ² is a hydrogen atom.)
It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4. The hot-press molded body according to claim 1,
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in the lignocellulose are represented by the following formula (1):

It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.1 to 0.4. The hot-press molded body according to claim 1,
The above-mentioned chemically modified lignocellulose has the properties (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.3. The hot-press molded body according to any one of claims 1 to 3,
The lignin component content of the chemically modified lignocellulose is 2 to 40% by mass,
Hot-pressed body.   5. A hot-press molded body according to any one of claims 1 to 4, further comprising a thermoplastic resin. A method for producing a hot-pressed product of chemically modified lignocellulose,
Comprising a step of compressing a fiber assembly composed of chemically modified lignocellulose fibers under heating,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (1):

It is half-esterified with a carboxy group-containing acyl group represented by
Or
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-1) the degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.01 to 0.4,
Or
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.4. A method for producing a hot-press molded body according to claim 6,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-1) Some of the hydroxyl groups present in the lignocellulose are represented by the following formula (1):

It is half-esterified with a carboxy group-containing acyl group represented by
Characteristic (b)
(B-1) The degree of substitution of the hydrogen atom of the hydroxyl group in the half-esterified lignocellulose is 0.1 to 0.4. A method for producing a hot-press molded body according to claim 6,
The method for producing a hot-pressed product, wherein the chemically modified lignocellulosic fiber has the characteristics (a) and (b):
Characteristic (a)
(A-2) Some of the hydroxyl groups present in lignocellulose are represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1.)
Etherified with a carboxyalkyl group represented by
Characteristic (b)
(B-2) The substitution degree of the hydrogen atom of the hydroxyl group in the etherified lignocellulose is 0.01 to 0.3. A method for producing a hot-press molded body according to any one of claims 6 to 8,
The average fiber diameter of the chemically modified lignocellulose fiber is 20 nm to 50 μm,
A method for producing a hot-pressed product. A method for producing a hot-press molded body according to any one of claims 6 to 9,
The lignin component content of the chemically modified lignocellulose fiber is 2 to 40% by mass,
A method for producing a hot-pressed product. A method for producing a hot-press molded body according to any one of claims 6 to 10,
A method for producing a hot-pressed product, wherein a temperature at which the fiber assembly composed of the chemically modified lignocellulose fibers is heated is 160 to 240 ° C, and a pressure at which the fiber assembly is compressed is 30 MPa to 100 MPa. A method for producing a hot-press molded body according to any one of claims 6 to 11,
A method for producing a hot-pressed product, wherein a fiber assembly further comprising a thermoplastic resin is used as a fiber assembly composed of chemically modified lignocellulose fibers. A method for producing a hot-pressed product of chemically modified lignocellulose,
A method for producing a hot-pressed product, comprising the following first step and second step:
(1) First step :
(A-1) In lignocellulose fiber, the following formula (3):

A part of the hydroxyl group present in the lignocellulose is reacted with a succinic anhydride or a derivative thereof represented by the following formula (1):

By half-esterification with a carboxy group-containing acyl group represented by
The step of producing a chemically modified lignocellulose fiber by setting the substitution degree of the hydrogen atom of the hydroxyl group in the lignocellulose to be half-esterified to 0.01 to 0.4,
Or
(A-2) In lignocellulose fiber, the following formula (4):
X- (CH ₂ ) _n -COOH (4)
(In the formula, n represents an integer of 1 to 3. X represents a halogen atom selected from the group consisting of Cl, Br and I.)
Is reacted with a halogenoalkyl carboxylic acid represented by the following formula (2):
-(CH ₂ ) _n -COOH (2)
(In the formula, n represents an integer of 1 to 3.)
By etherification with a carboxyalkyl group represented by
The step of producing chemically modified lignocellulose fibers by setting the degree of substitution of hydrogen atoms of hydroxyl groups in the lignocellulose to be etherified to 0.01 to 0.4,
(2) Second step :
A step of compressing the fiber assembly made of the chemically modified lignocellulose fiber obtained in the first step under heating. A method for producing a hot-press molded body according to claim 13,
A method for producing a hot-pressed product, wherein a temperature at which the fiber assembly composed of the chemically modified lignocellulose fibers is heated is 160 to 240 ° C, and a pressure at which the fiber assembly is compressed is 30 MPa to 100 MPa.