U.S. patent application number 12/003057 was filed with the patent office on 2008-10-23 for novel lignin derivatives, molded products using the same and processes for making the same.
This patent application is currently assigned to KABUSHIKI KAISHA MARUTO. Invention is credited to Masamitsu Funaoka.
Application Number | 20080262182 12/003057 |
Document ID | / |
Family ID | 14181115 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080262182 |
Kind Code |
A1 |
Funaoka; Masamitsu |
October 23, 2008 |
Novel lignin derivatives, molded products using the same and
processes for making the same
Abstract
The present invention provides a process for producing novel
lignin derivatives, which comprises using a lignophenol derivative
containing a diphenylpropane unit formed by binding a carbon atom
at an ortho-position relative to a phenolic hydroxyl group of a
phenol derivative to a carbon atom at a benzyl-position of a
phenylpropane fundamental unit of lignin, and binding an oxygen
atom of the hydroxyl group and a .beta.-positional carbon atom
under alkali conditions under which the hydroxyl group can
dissociate, to obtain an arylcoumaran derivative containing an
arylcoumaran unit in which a coumaran skeleton is bound to an
aromatic ring of lignin.
Inventors: |
Funaoka; Masamitsu;
(Tsu-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
KABUSHIKI KAISHA MARUTO
Yokkaichi-shi
JP
MASAMITSU FUNAOKA
Tsu-shi
JP
|
Family ID: |
14181115 |
Appl. No.: |
12/003057 |
Filed: |
December 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11003212 |
Dec 2, 2004 |
7323501 |
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12003057 |
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10619930 |
Jul 15, 2003 |
6841660 |
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11003212 |
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09508592 |
Jun 5, 2000 |
6632931 |
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PCT/JP97/03240 |
Sep 12, 1997 |
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10619930 |
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Current U.S.
Class: |
527/401 ;
527/403 |
Current CPC
Class: |
C08H 6/00 20130101; Y02P
20/582 20151101 |
Class at
Publication: |
527/401 ;
527/403 |
International
Class: |
C08H 5/02 20060101
C08H005/02 |
Claims
1. A method of making a cross-linking material comprising: (a)
solvating lignin in ligno-cellulose material with phenol and/or a
phenol derivative having at least one unsubstituted ortho-position
or para-position with respect to a hydroxyl group of a phenol
group, (b) contacting the solvated lignin with concentrated acid,
thereby forming a carbon-carbon bond between the at least one
unsubstituted ortho-position or para-position of the phenol or the
phenol derivative and a benzyl position of a phenylpropane unit of
the lignin and forming cleavages of benzyl-aryl ether bonds,
whereby a lignophenol derivative having a plurality of
diphenylpropane units is formed, and (c) contacting the lignophenol
derivative with at least one cross-linking compound selected from
an aldehyde and a diisocyanate under alkaline conditions that will
dissociate the phenolic hydroxyl group, thereby forming a
cross-linking lignin-based polymer by introducing a cross-linking
functional group at the ortho-position, the para-position or both
the ortho-position and para-position with respect to the phenolic
hydroxyl group of the diphenylpropane unit.
2. A method as in claim 1, wherein the lignophenol derivative has
an UV adsorption maximum at about 280 nm, an ionization
differential maximum at about 300 nm and a shoulder peak at a
longer wavelength not observed in a UV spectrum.
3. A method as in claim 1, wherein the lignophenol derivative is
substantially soluble in methanol, ethanol, acetone, dioxane,
tetrahydrofuran, pyridine and dimethylformamide.
4. A method as in claim 1, wherein the lignophenol derivative has
substantially no benzyl hydroxyl groups at a side chain (.alpha.)
position of the diphenylpropane unit.
5. A method as in claim 1, wherein under said alkaline conditions,
.beta.-aryl ether bonds are cleaved between diphenylpropane units
within the cross-linking based polymer.
6. A method as in claim 1, wherein step (c) is performed at about
40-80.degree. C.
7. A method as in claim 1, wherein the cross-linking compound is
formaldehyde.
8. A method as in claim 1, wherein the phenol derivative is
m-cresol or p-cresol.
9. A method as in claim 1, wherein the phenol derivative is
2,4-xylenol or 2,6-xylenol.
10. A method as in claim 1, further comprising mixing a molding
substrate material with the cross-linking lignin-based polymer,
wherein the cross-linking lignin-based polymer acts as a binder for
the molding substrate material.
11. A method as in claim 10, further comprising heating the mixture
of the molding substrate material and the cross-linking
lignin-based polymer in order to induce cross-linking functional
groups to cross-link.
12. A method as in claim 1, wherein the lignophenol derivative: (a)
has an UV adsorption maximum at about 280 nm, an ionization
differential maximum at about 300 nm and a shoulder peak at a
longer wavelength not observed in a UV spectrum, (b) is
substantially soluble in methanol, ethanol, acetone, dioxane,
tetrahydrofuran, pyridine and dimethylforamide, and (c) has
substantially no benzyl hydroxyl groups at a side chain (.alpha.)
position of the diphenylpropane unit.
13. A method as in claim 12, wherein the cross-linking compound is
formaldehyde.
14. A method as in claim 13, wherein the phenol derivative is
m-cresol or p-cresol.
15. A method as in claim 13, wherein the phenol derivative is
2,4-xylenol or 2,6-xylenol.
16. A method as in claim 15, further comprising mixing a molding
substrate material with the cross-linking lignin-based polymer,
wherein the cross-linking lignin-based polymer acts as a binder for
the molding substrate material.
17. A method as in claim 16, further comprising heating the mixture
of the molding substrate material and the cross-linking
lignin-based polymer in order to cross-link the cross-linking
functional groups.
18. A method as in claim 14, further comprising mixing a molding
substrate material with the cross-linking lignin-based polymer,
wherein the cross-linking lignin-based polymer acts as a binder for
the molding substrate material.
19. A method as in claim 18, further comprising heating the mixture
of the molding substrate material and the cross-linking
lignin-based polymer in order to induce cross-linking functional
groups to cross-link.
20. A cross-linking lignin based polymer formed by the method of
claim 1.
21. A cross-linking lignin based polymer formed by the method of
claim 7.
22. A cross-linking lignin based polymer formed by the method of
claim 8.
23. A cross-linking lignin based polymer formed by the method of
claim 9.
24. A cross-linking lignin based polymer formed by the method of
claim 12.
Description
TECHNICAL FIELD
[0001] The present invention relates to a technical field of
utilizing lignophenol derivatives obtained by phenol-derivatizing
lignin, which are one component of timber. More particularly, the
present invention relates to the technical field in which molded
products are produced using novel materials obtained by further
secondarily treating lignophenol derivatives with these materials
and molding materials are recovered from the molded product for
reuse.
BACKGROUND OF THE INVENTION
[0002] Recently, there has been increased an interest in forest
resources that can be continuously used as industrial raw
materials, instead of fossil resources, such as petroleum, coal and
the like, which have been predicted to be depleted. Such a forest
resource, i.e., a lignocellulose resource, is composed of
hydrophilic carbohydrates, such as cellulose, hemicellulose and the
like, and a hydrophobic lignin (polyphenol), which form the
interpenetrating network (IPN) structure and an complicated complex
in the cell wall. The lignocellulose resource imparts useful
properties to various materials, because of the structure of the
complex.
[0003] Two methods are known for utilizing the known lignocellulose
resource, i.e. timber. One is a direct utilization of the
lignocellulose material by cutting or machining the lignocellulose
resource, i.e., the complex itself, and processing it into
construction materials or furniture building materials having a
predetermined shape, or processing the lignocellulose resource into
chips or fibers for manufacturing molded products. The other is an
indirect utilization of the lignocellulose material by extracting
only cellulose, a component of the complex, and making a pulp of
the product.
[0004] In view of the expected depletion of fossil resources in the
future, the reuse of lignocellulose resources is important in the
both utilization forms.
[0005] However, in the current situation, if a construction
material is prepared according to the direct utilization method, it
will have a predetermined shape and be comparatively large;
therefore, treatments such as grinding and finely-dividing are
usually necessary to reuse the construction material. In addition,
thermosetting resins used in molded products are difficult to
separate from wood chips and fibers. Therefore, in the direct
utilization form, after the first use, a portion of the
lignocellulose resource is discarded, in many cases without
reuse.
[0006] Moreover, in the indirect utilization form, only cellulose
is recovered and utilized to make a fiber or sheet.
[0007] Similarly, in the direct utilization form, the entire
lignocellulose resource, i.e., cellulose and lignin, are not reused
and, also in the indirect utilization form, lignin, which is one
component of the lignocellulose resource, may be reused or not
reused under in certain circumstances.
[0008] Lignin is an organic substance that exists in large amounts
intermingled with cellulose. The present inventor considered the
function of lignin as a complex constituting material and
previously filed two applications that are directed to extraction
of lignin from the lignocellulose resource in a functionalized
form. The first application is Japanese Application No. 1-55686
(JP-A 2-233701) and the second application is Japanese Application
No. 8-92695 (unpublished as of the filing date of this
corresponding International application). The first application
teaches methods of bonding a phenol derivative to the
lignocellulose resource and, thereafter, contacting the
lignocellulose resource with sulfuric acid, whereby lignin is
separated from cellulose, because lignin has a bound phenol
derivative. In addition, the second application teaches processes
for manufacturing a novel cellulose-lignin molded product by using
the hybrid lignin, which was provided in the first application, as
a binder for a molded cellulose material.
DISCLOSURE OF THE INVENTION
[0009] Accordingly, an object of the present invention is to
provide novel materials having improved functions that are formed
by further secondarily-treating this hybrid lignin and to provide
cellulose molded products utilizing these novel materials. In
addition, another object is to provide methods for reusing the
cellulose molded products by utilizing these novel materials.
[0010] In order to accomplish the aforementioned objects, the
present inventor made the following inventions.
[0011] That is, a first invention is a novel process for producing
a lignin derivative, which comprises using a lignophenol derivative
containing a diphenylpropane unit formed by binding a carbon atom
at an ortho-position relative to a phenolic hydroxyl group of a
phenol derivative to a carbon atom at a benzyl-position of a
phenylpropane fundamental unit of lignin, and binding an oxygen
atom of the hydroxyl group to a .beta.-positional carbon atom under
alkali conditions, by which the hydroxyl group can dissociate, to
obtain an arylcoumaran derivative containing an arylcoumaran unit
in which a coumaran skeleton is bound to an aromatic ring of a
phenylpropane unit of lignin. In this invention, the aforementioned
phenol derivative is preferably p-cresol.
[0012] A second invention is a novel lignin derivative (hereinafter
referred to as "an arylcoumaran derivative") represented by the
following chemical formula and having an arylcoumaran unit in which
a coumaran skeleton is bound to an aromatic ring of a lignin
phenylpropane unit.
[0013] Chemical formula:
##STR00001##
[0014] A third invention is a process for producing a novel lignin
derivative, which comprises heating a lignophenol derivative
containing a diphenylpropane unit formed by binding an aromatic
carbon atom of a phenol derivative to a carbon atom at a
benzyl-position of a phenylpropane fundamental unit of lignin, with
a cross-linking functional group forming compound under alkali
conditions, by which the introduced phenolic hydroxyl group of a
phenol derivative and/or a phenolic hydroxyl group originally
existing in lignin can dissociate, to introduce a cross-linking
functional group at an ortho-position and/or a para-position of the
phenolic hydroxyl group, thereby obtaining a lignin cross-linking
derivative containing a diphenylpropane unit having a cross-linking
functional group.
[0015] In this invention, preferably, the phenol derivative is
p-cresol, the cross-linking functional group forming compound is
formaldehyde and the cross-linking functional group is a
hydroxymethyl group.
[0016] A fourth invention is a novel lignin derivative (hereinafter
referred to as "a lignin cross-linking derivative") having a
cross-linking functional group at an ortho-position and a
para-position of a phenolic hydroxyl group of a lignophenol
derivative containing a diphenylpropane unit formed by binding an
aromatic carbon atom of a phenol derivative to a carbon atom at a
benzyl-position of a phenylpropane fundamental unit of lignin. In
this lignin derivative, a preferable cross-linking functional group
is a hydroxymethyl group.
[0017] A fifth invention is molded products formed by molding
fibrous, chip-like, or powdery substrate materials, characterized
in that said molded products contain an arylcoumaran
derivative.
[0018] This molded product has increased strength and
water-resistance because of the connection of substrate molding
materials using the arylcoumaran derivative. In addition, the
arylcoumaran derivative can be easily extracted from a molded
product using a solvent having affinity for the arylcoumaran
derivative and can be separated from the molding material.
[0019] In this invention, the substrate molding material preferably
is cellulose fiber, because cellulose fibers are readily available
and are easily separated from the arylcoumaran derivative for reuse
in a variety of ways.
[0020] A sixth invention is a molded product produced by molding
fibrous, chip-like, or powdery substrate molding materials,
characterized in that said molded product contains the
aforementioned lignin cross-linking derivative.
[0021] This molded product has increased strength and
water-resistance if molding substrate materials are bound by the
lignin cross-linking derivative. Preferably, the lignin
cross-linking derivatives are cross-linked, because cross-linking
further increases strength and water-resistance.
[0022] A seventh invention is a method of treating a molded
product, which comprises adding a solvent having affinity for this
arylcoumaran derivative to a molded product containing the
arylcoumaran derivative to recover the arylcoumaran derivative.
[0023] According to this invention, the arylcoumaran derivative is
a binder material and can be reused and efficiently extracted arid
separated from a molded product. In addition, using this treatment,
a molding substrate material can be reusably separated at the same
time.
[0024] In this invention, the molding material preferably is
cellulose fiber.
[0025] When the molding material is cellulose fiber, as a result of
treatment with a solvent having affinity for a lignophenol
derivative, the cellulose fiber is also readily separated.
[0026] Timber, waste timber, end timber, herbaceous plants,
agricultural waste and the like can be used as the lignocellulose
material and thus, lignocellulose materials are efficiently used
and reused.
[0027] Further, in this invention, the molding material preferably
is cellulose fiber obtained by splitting a lignocellulose
material.
[0028] When the molding material is a cellulose fiber obtained by
splitting a lignocellulose material, a novel molded product is
formed using a lignocellulose material. Moreover, cellulose fiber
is readily available and is easily separated from a lignophenol
derivative, which is utilized again in a variety of ways. In
particular, when a lignophenol derivative is obtained from a
lignocellulose material, both the cellulose component and the
lignin component are efficiently used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is the structural formula showing a phenylpropane
unit of lignin.
[0030] FIG. 2 is a view showing a structure that may be derivatized
at an .alpha.-position and a .beta.-position of the phenylpropane
unit of lignin.
[0031] FIGS. 3 (a) to 3 (d) are views illustrating examples in
which a sub-unit is derivatized at an aromatic ring of the
phenylpropane unit of lignin.
[0032] FIG. 4 is a view showing a first method for synthesizing a
lignophenol derivative.
[0033] FIG. 5 is a view showing a second method for synthesizing a
lignophenol derivative.
[0034] FIG. 6 is a view showing the reaction of lignin with a
phenol derivative using concentrated sulfuric acid at an interface
of a phenol derivative phase in a two phase phenol
derivative/concentrated sulfuric acid solution.
[0035] FIG. 7 is a view showing a schematic in which a phenol
derivative is selectively introduced at an .alpha.-position of a
lignin sidechain.
[0036] FIG. 8 is a view showing a partial structure of lignin that
has undergone structural conversion by introduction of a phenol
derivative at an .alpha.-position of a lignin sidechain.
[0037] FIG. 9 (a) shows a UV spectrum of ground lignin and FIG. 9
(b) shows a UV spectrum of a lignophenol derivative.
[0038] FIG. 10 (a) shows a differential spectrum of ground lignin
and FIG. 10 (b) shows a differential spectrum of a lignophenol
derivative.
[0039] FIG. 11 (a) is an IR spectrum of ground lignin, FIG. 11 (b)
is an IR spectrum of a lignin sulfate, and FIG. 11 (c) is an IR
spectrum of a lignophenol derivative.
[0040] FIG. 12 (a) is an .sup.1H-NMR spectrum of an acetate
compound of a lignophenol derivative and FIG. 12 (b) is an
.sup.1H-NMR spectrum of an acetate compound of ground lignin.
[0041] FIG. 13 is a diagram showing the yields of lignophenol
derivatives from lignocellulose materials of various origins.
[0042] FIG. 14 is a diagram showing elementary analysis results, an
amount of introduced cresol, appearances, and a dissolving solvent
for lignophenol derivatives obtained from lignocellulose materials
of various origins.
[0043] FIG. 15 is a diagram showing the distribution of hydroxyl
groups in lignophenol derivatives obtained from lignophenol
materials of various origins.
[0044] FIG. 16 is a view showing a sub-unit of a lignophenol
derivative that is used to synthesize an arylcoumaran
derivative.
[0045] FIG. 17 is a view showing an arylcoumaran unit.
[0046] FIG. 18 is a view showing one example of an arylcoumaran
unit obtained from a lignophenol derivative obtained by using
p-cresol as a phenol derivative.
[0047] FIG. 19 is one example of a UV spectrum of an arylcoumaran
derivative.
[0048] FIG. 20 is one example of an IR spectrum of an arylcoumaran
derivative.
[0049] FIG. 21 is a view showing one example of a UV spectrum of a
lignin cross-linking derivative.
[0050] FIG. 22 is a view showing one example of an IR spectrum of a
lignin cross-linking derivative.
[0051] FIG. 23 is a view showing one example of a lignin structural
conversion to a lignophenol derivative using p-cresol as a phenol
derivative, an arylcoumaran derivative and a lignin cross-linking
derivative.
[0052] FIG. 24 is a view showing principal aspects of a nucleus
exchange method.
[0053] FIG. 25 is a view showing principal aspects of a
periodate-oxidation treatment.
[0054] FIG. 26 is a view showing one example of the structural
analysis in which a nucleus-exchange method and a
periodate-oxidation method are applied to an arylcoumaran
derivative.
[0055] FIG. 27 is a view showing steps for manufacturing a molded
cellulose product using a secondary derivative.
[0056] FIG. 28 is a view showing steps for manufacturing a molded
cellulose product using a secondary derivative.
[0057] FIG. 29 is a view showing transference of a secondary
derivative upon removal by distillation of a solvent from a molded
product, which solvent had solvated the secondary derivative.
[0058] FIG. 30 is a view showing steps for manufacturing a molded
cellulose product using a secondary derivative.
[0059] FIG. 31 is a view showing steps for manufacturing a molded
cellulose product using a secondary derivative.
[0060] FIG. 32 is a view showing steps for recovering a secondary
derivative and a substrate constituting material from a molded
product.
[0061] FIG. 33 is a view showing the steps of examples 1 to 3.
[0062] FIG. 34 is a diagram showing the properties of a lignophenol
derivative and an arylcoumaran derivative, which is a derivative
thereof.
[0063] FIG. 35 is a diagram showing the distribution of hydroxyl
groups and the phenolic frequency for a lignophenol derivative and
an arylcoumaran derivative, which is a derivative thereof.
[0064] FIG. 36 is a diagram showing the properties of a lignophenol
derivative and a lignin cross-linking derivative, which is a
derivative thereof.
[0065] FIG. 37 is a diagram showing the distribution of hydroxyl
groups and the phenolic frequency for a lignophenol derivative and
a lignin cross-linking derivative, which is a derivative
thereof.
[0066] FIG. 38 is a view showing the state where a test piece is
supported and a load is applied in a strength test.
[0067] FIG. 39 (a) is a graphical view showing Pmax; FIG. 39 (b) is
a view showing MOE; FIG. 39 (c) is a view showing MOR.
[0068] FIG. 40 is a graphical view showing volumetric change rates
of a molded cellulose product using a lignophenol derivative.
[0069] FIG. 41 is a graphical view showing volumetric change rates
of a molded cellulose product using an arylcoumaran derivative.
[0070] FIG. 42 is a graphical view showing volumetric change rates
of molded cellulose products using a lignophenol derivative, an
arylcoumaran derivative and a lignin cross-linking derivative,
respectively, by comparison.
[0071] FIG. 43 is a diagram showing a comparison of
water-absorption and volumetric change rates for molded cellulose
products using a lignophenol derivative, an arylcoumaran derivative
and a lignin cross-linking derivative, respectively.
[0072] FIG. 44 is a diagram showing recovery rates of various
derivatives from a molded product.
BEST MODES FOR CARRYING OUT THE INVENTION
[0073] Modes for carrying out the present invention will be
explained in detail below.
[0074] In the present invention, an arylcoumaran polymer and a
cross-linking lignin derivative are produced from a lignocellulose
material containing lignin. The lignocellulose material containing
lignin refers to the woody part of a plant. More particularly,
various trees such as coniferous trees, broadleaf trees, and
various herbaceous plants, such as rice, corn, beet and the like,
can be used as a raw material for the lignocellulose material. In
addition, although the lignocellulose material can be used in any
form such as powder, chips or the like, a powder lignocellulose
material has advantages for efficiently extracting the lignophenol
derivative. Moreover, the lignocellulose material may be a waste
timber or an end timber of a lignocellulose material, or a feed or
an agricultural waste containing a lignocellulose material may be
used.
[0075] In order to produce an arylcoumaran derivative or a lignin
cross-linking derivative from the lignocellulose material, a phenol
derivative must first be bound to the lignin of the lignocellulose
material to produce a lignophenol derivative from the
lignocellulose material, in which a phenol derivative is introduced
exclusively at an .alpha.-position (benzyl-position) of a sidechain
of a phenylpropane unit, which forms the lignin skeleton (this step
is referred to as a first derivatization step).
[0076] In the present specification, the phenylpropane unit in
lignin refers to a unit, of which the fundamental skeleton is a
structure of the 9 carbons shown in the structural formula of FIG.
1. In this structure, the symbol --O(H) shown bound to an aromatic
ring means that, in some cases, a hydrogen atom is bound to the
oxygen atom of the aromatic ring, thereby forming a hydroxyl group
and in some case, this oxygen atom together with another
phenylpropane unit constitutes an ether linkage.
[0077] Within this phenylpropane unit is included an unit in which
various structures shown in FIG. 2 are substituted at an
.alpha.-position or a .beta.-position of a sidechain of the
fundamental unit of the aromatic ring. Also included is a unit in
which an aromatic ring is bound to another substituent or another
phenylpropane unit. Four examples are shown in FIGS. 3 (a) to (d)
as examples of various aromatic rings having other substituents.
The other aromatic rings include one or two methoxyl groups bound
to an ortho-position relative to a phenolic or ethereal hydroxyl
group, or one methoxyl group is bound to one or ortho-position and
a carbon atom, which binds to the other fundamental unit that is
bound to the other ortho-position.
[0078] Hereinafter, in the present specification and drawings, the
aromatic rings derived from a phenylpropane unit of lignin, which
are described in the specification and in the drawings, are
intended to include all such variations.
[0079] In the present invention, a material having more functional
features is formed by introducing the predetermined phenol
derivative at this .alpha.-position to decrease the structural
irregularity of lignin and further secondarily-derivatized the
resulting lignophenol derivative.
[0080] Currently, there are two methods for extracting lignin in a
lignocellulose material as a lignophenol derivative. In this
example, lignophenol derivative means a polymer containing a
diphenylpropane unit in which a phenol derivative is introduced at
an .alpha.-position of a sidechain of a phenylpropane unit of
lignin via a C--C linkage. The amount and molecular weight of the
introduced phenol derivative in this polymer varies depending upon
the lignocellulose material used as a raw material and the reaction
conditions.
[0081] The first method is a method described in the first
application noted above (JP-A 2-233701).
[0082] In this method, for example, a lignocellulose material, such
as wood powder or the like, is mixed with a liquid phenol
derivative (such as cresol or the like) to dissolve the lignin in
the phenol derivative. Then, concentrated sulfuric acid (for
example, 72% sulfuric acid) is added to the lignocellulose material
to mix and to dissolve the cellulose component. According to this
method, the phenol derivative containing the dissolved lignin and
the concentrated sulfuric acid containing the dissolved cellulose
component form a two phase solution. Lignin dissolved in the phenol
derivative only contacts the acid at an interface in which the
phenol derivative phase contacts the concentrated acid phase. As a
result, a cation at a sidechain .alpha.-position (benzyl-position),
which is a highly reactive site of a lignin fundamental constituent
unit and is produced by contact with the acid, binds to the phenol
derivative. As a result, the phenol derivative is introduced at the
.alpha.-position via a C--C linkage. In addition, a benzyl aryl
ether linkage is made into low molecular species by cleavage. As a
result, lignin is made into low molecular species and a lignophenol
derivative, in which a phenol derivative is introduced at a
benzyl-position of a fundamental constituent unit thereof, is
produced in the phenol derivative phase (see FIG. 6). The
lignophenol derivative is then extracted from this phenol
derivative phase. The lignophenol derivative is obtained as a part
of an aggregate of low molecular weight lignin that has been made
into a low molecular species by cleavage of the benzyl aryl ether
linkage in the lignin. Methods for introducing a phenol derivative
at a benzyl-position via a phenolic hydroxyl group are known.
[0083] Extraction of the lignophenol derivative from the phenol
derivative phase can be performed, for example, according to the
following method. That is, the phenol derivative phase is added to
a large excess of ethyl ether to obtain precipitates that are
collected and dissolved in acetone. Acetone insoluble products are
removed by centrifugation and the acetone-soluble products are
concentrated. The acetone-soluble products are added dropwise to a
large excess of ethyl ether and the precipitate fractions are
collected. The solvent is distilled off from the precipitate
fractions and the precipitate fractions are dried in a desiccator
with phosphorus pentaoxide to obtain a low-molecular weight crude
lignophenol derivative containing the lignophenol derivative as a
dried portion. In addition, the crude lignophenol derivative can be
also obtained by removing the phenol derivative phase by simple
distillation under reduced pressure. Moreover, the acetone-soluble
products can be used as such as a lignophenol derivative solution
in the secondarily-derivatized treatment.
[0084] In a second method, after a lignocellulose material is mixed
with a solvent (for example, ethanol or acetone), which dissolves a
solid or liquid phenol derivative, the solvent is distilled off as
shown in FIG. 5 (phenol derivative sorbing step). Next, a
concentrated acid is added to this lignocellulose material to
dissolve the cellulose component. As a result, similar the first
method, for lignin dissolved with the phenol derivative, a cation
at a highly reactive site (sidechain .alpha.-position) of lignin
that was produced by contact with the concentrated acid binds to
the phenol derivative and the phenol derivative is introduced
therein. In addition, lignin is made into low molecular weight
species by cleavage of the benzyl aryl ether linkage. The
properties of the resulting lignophenol derivative are not
different from those obtained by the first method. Then, the
lignophenol derivative is extracted by a liquid phenol derivative.
Extraction of the lignophenol derivative from the liquid phenol
derivative phase can be performed in the same manner as that of the
first method. Alternatively, the whole reaction solution, after
treatment with a concentrated acid, is placed into an excess of
water and the insoluble fractions are collected, dialyzed and
dried. Acetone or alcohol is added to this dried material and the
lignophenol derivative is extracted. In addition, similar to the
first method, this soluble fraction is added dropwise to an excess
of ethyl ether or the like and the lignophenol derivative is
obtained as an insoluble fraction.
[0085] Also in this method, similarly, an acetone-soluble product
can be used as a lignophenol derivative solution for the
secondarily-derivatizing treatment.
[0086] Of these two kinds of methods, the second method, which is a
method for extracting and separating a lignophenol derivative with
acetone or alcohol, is economical, because less phenol derivative
is used. In addition, because this method can treat a large amount
of lignocellulose material with a lessor amount of a phenol
derivative, it is suitable for large scale synthesis of
lignocellulose derivatives.
[0087] FIG. 7 shows a schematic in which a phenol derivative is
selectively introduced at an .alpha.-position of the lignin
sidechain by these methods. Introduction of the phenol derivative
at a phenylpropane unit of lignin and the amount that is introduced
can be confirmed by .sup.1H-NMR. Selective introduction at an
.alpha.-position of a sidechain of a phenylpropane unit also can be
confirmed by .sup.1H-NMR and nucleus-exchange analysis.
[0088] Moreover, in FIG. 8, a step for converting natural lignin
into a lignophenol derivative by these methods is represented by
showing a change in a partial structure of the lignophenol
derivative.
[0089] In addition, FIGS. 9 (a) and 9 (b) show a UV spectrum of a
sample of milled wood lignin (hereinafter referred to as "ground
lignin") obtained from defatted wood powder by a Bjorkman method
and a lignophenol derivative (lignocresol) sample in the case in
which cresol was introduced as the phenol derivative into the
lignocellulose material. FIGS. 10 (a) and 10 (b) show an ionization
differential spectrum (.DELTA.Ei spectrum) of the respective
samples of FIGS. 9 (a) and 9 (b). In FIGS. 9 (a) and (b) and FIGS.
10 (a) and (b), the lignophenol derivative shows a very sharp peak
at 280 nm and 300 nm, respectively. Moreover, a shoulder peak that
was observed at the longer wavelength side in the previous lignin
samples was not seen at all in a lignocellulose derivative. This
result shows that little complicated secondary structural change,
such as generation of a conjugated system other than the selective
phenolization at the sidechain .alpha.-position in the lignin
phenylpropane unit, is produced in the first derivatized step and
that, accordingly, the conjugated system disappears and the
structural diversity is diminished. The lignocresol used was
obtained by mixing 10 ml of p-cresol with 20 ml of 72% sulfuric
acid per 1 g of wood powder and stirring at 25.degree. C. for 60
minutes according to the aforementioned first method. After
measurement of the UV spectrum, the sample was dissolved in methyl
cellulose. After measurement of the .DELTA.Ei spectrum,
measurements were performed using methyl cellulose and 1N sodium
hydroxide solution.
[0090] FIGS. 11 (a) to 11 (c) show an IR spectrum (KBr method) of a
ground lignin sample, a lignin sulfate sample (FIG. 11 (a))
prepared from defatted wood powder using a Tappi method, and the
lignophenol derivative (lignocresol) (FIG. 11 (b)) used in FIG. 9
(b). IR spectrum of the lignophenol derivative has a very sharp
absorption as compared with lignin sulfate prepared using only 72%
sulfuric acid and it demonstrates that auto-condensation, which
would make the molecule rigid, is not generated. In addition,
little absorption is apparent near 1650 cm.sup.-1, which would be
attributable to a conjugated carbonyl group. Conversely, a strong
absorption based on the adjacent 2H of a phenol ring is apparent
near 800 cm.sup.-1. This result is more consistent with that of the
UV spectrum.
[0091] FIGS. 12 (a) and 12 (b) show an .sup.1H-NMR spectrum of the
lignophenol derivative (lignocresol) used in FIGS. 9 (a) and 9 (b),
the acetate thereof (FIG. 12 (a)), and the acetate of a ground
lignin sample (FIG. 12 (b)). Although the acetoxy proton area
(1.6-2.5ppm) overlaps with a methyl proton of the introduced
cresol, it is clear that, from the signal pattern, the lignophenol
derivative has many phenolic hydroxyl groups and still retains an
aliphatic hydroxyl group. In addition, a methoxyl proton and an
aliphatic sidechain proton (2.50-5.20 ppm) are clearly apparent and
thus, it is believed that the irregularities of the natural lignin
have been reduced. In addition, from the integrated values of the
various peaks in these spectra, the amount of the aliphatic
hydroxyl group and the aromatic hydroxyl group can be quantified
and the amount of introduced phenol derivative (p-cresol in this
spectrum) can be also quantified.
[0092] FIG. 13 shows the yields of lignophenol derivatives obtained
by introducing p-cresol as a phenol derivative into lignocellulose
materials (wood powder) of various origins (expressed as weight %
relative to the lignin contained in wood powder and the yield
includes introduced cresol). Little difference in the separating
are observed among tree species for both coniferous trees and
broadleaf trees. In addition, these lignophenol derivatives are
obtained by using 10 ml of p-cresol and 20 ml of 72% sulfuric acid
per 1 g of wood powder according to the aforementioned first
method.
[0093] FIG. 14 shows the properties (elementary analysis results,
the amount of introduced cresol, appearances and dissolving
solvent) of various lignocresol samples produced by introducing
cresol into lignocellulose materials (wood powder) of various
origins (those obtained under the same conditions as those for the
lignocellulose material of FIG. 10). As compared with the ground
lignin sample, which is believed to have little structural change
in the isolating step, the lignophenol derivative has 5% higher
carbon content and 5% lower oxygen content based on cresol binding
for both coniferous trees and broadleaf trees. Introduced cresol is
about 25% (about 0.65 mol/C9) in coniferous trees and about 30%
(about 0.9 mol/C9) in broadleaf trees and it has been proved that
more than 90% of the binding positions are the sidechain
.alpha.-position. In addition, the weight-average molecular weight
is 3000-4000 in the lignophenol derivative derived from coniferous
trees and is slightly lower in broadleaf trees. Further, the
lignophenol derivative rapidly dissolves in various solvents, such
as methanol, ethanol, acetone and the like.
[0094] In addition, the lignophenol derivative had a slightly
pinkish-white appearance, even though it was treated with a
concentrated acid and a large amount of cresol was introduced. This
is greatly different from the lignin phenolized with a sulfuric
acid or hydrochloric acid catalyst, which had a black color.
[0095] FIG. 15 shows the amount of hydroxyl group in lignophenol
derivatives (lignocresol) obtained from various origins using the
same conditions as those for the samples in FIGS. 10 (a) and 10
(b). The lignophenol derivative does not have a benzyl hydroxyl
group at a sidechain .alpha.-position and on the other hand, the
sidechain .gamma.-positional hydroxyl group is retained in the same
amount as that of a ground lignin. Phenolic hydroxyl groups are
greatly increased as a result of cleavage of the benzyl aryl ether
in lignin and introduction of cresol in the treating process.
(Lignophenol Derivative as a Starting Material for Synthesizing an
Arylcoumaran Polymer)
[0096] A lignophenol derivative, which is used for synthesizing an
arylcoumaran polymer of the present invention, requires that the
carbon at an ortho-position relative to a phenolic hydroxyl group
of introduced phenol derivative is bound to a sidechain
.alpha.-positional carbon of a phenylpropane unit of lignin. That
is, the fundamental structure shown in FIG. 16 is required. In FIG.
16, the aromatic ring of the introduced phenol has no substituents
other than hydrogen. However, in the present invention, the
introduced phenol ring of the lignophenol derivative is not
intended to be limited to such a structure and it may have other
substituents. In the present specification, claims and drawings,
the phenol derivative that is introduced into a phenylpropane unit
is described and expressed in drawings is intended to include
phenol derivatives having various substituents.
[0097] Because the phenolic hydroxyl group of such introduced
phenols dissociates under alkali conditions and an arylcoumaran
structure is formed by rearrangement with the adjacent groups, the
phenol derivative for synthesizing a lignophenol derivative, which
is then used to synthesize an arylcoumaran polymer of the present
invention, simply requires that at least one ortho-position
relative to one phenolic hydroxyl group is free, that is, there is
no substituent at that position, because this ortho-position will
become a site for binding to the main lignin structure. More
particularly, monovalent phenol derivatives, such as phenol,
alkylphenols, such as cresol and the like, methoxyphenol, naphthol
and the like, divalent phenol derivatives, such as catechol,
resorcinol and the like, and trivalent phenol derivatives, such as
pyrogallol and the like, are appropriate, because these derivatives
do not have any substituents at an ortho-position relative to a
phenolic hydroxyl group.
[0098] Confirmation of the formation of such lignophenol
derivatives can be confirmed by .sup.1H-NMR and nucleus exchange
analysis.
(Lignophenol Derivative as a Starting Material for Synthesizing a
Cross-Linking Lignin Derivative)
[0099] The lignophenol derivatives, which can be used to synthesize
a cross-linking lignin derivative of the present invention, are not
particularly limited. In the present invention, a cross-linking
functional group is introduced into a site that is an
ortho-position or para-position relative to the phenolic hydroxyl
group, which introduction site inherently exists in the
phenylpropane unit of lignin, because when the cross-linking
functional group is introduced into any site of a diphenylpropane
unit of a lignophenol derivative, a cross-linking lignin derivative
is formed.
[0100] Increase in an introduced amount and adjustment of an
introduced amount by introducing a cross-linking functional group
also on the introduced phenol derivative side can be accomplished
by selecting the phenol derivative to be introduced.
[0101] That is, because the cross-linking functional group is
introduced at the ortho-position or para position relative to the
phenolic hydroxyl group under alkaline conditions by which a
phenolic hydroxyl group dissociates, when at least one of the
ortho-position or the para-position relative to the phenolic
hydroxyl group of the introduced phenol is free in a lignophenol
derivative, the cross-linking functional group also will be
introduced at the introduced phenol derivative side.
[0102] In order to produce the lignophenol derivative of the
present invention, because the sidechain .alpha.-positional carbon
of the lignin phenylpropane unit and the carbon that is
ortho-position or para-position relative to phenol derivative
phenolic hydroxyl group are bound together, in order to obtain a
cross-linking lignin derivative when at least two sites of two
positions and one para-position relative to one phenolic hydroxyl
group are free, one site becomes a site for binding to the
phenylpropane unit and thereafter, another cross-linking functional
group introducing site can remain.
[0103] Conversely, if a lignophenol derivative in which a phenol
derivative having substituents at two or more sites among an
ortho-position and a para-position relative to the phenolic
hydroxyl group is used, such as 2,4-xylenol, 2,6-xylenol and the
like, because a cross-linking functional group introducing site is
no longer present in the introduced phenyl derivative, only the
cross-linking functional group will be introduced into the main
lignin structure.
[0104] Therefore, by combining a phenol derivative having a
cross-linking functional group introducing site and a different
reactivity with a phenol derivative having no or a different
introducing site number, or combining two or more of them, the
number of sites for introducing a cross-lining functional group in
a lignophenol derivative can be controlled and as a result, the
cross-linking degree of the cross-linking lignin derivative can be
controlled.
[0105] Preferred phenol derivatives, which can also introduce a
cross-linking functional group at an introduced phenol derivative
side, are phenol and cresol (particularly, m-cresol). In addition,
preferred phenol derivatives, which do not introduce a
cross-linking functional group into the introduced phenol
derivative, are 2,4-xylenol and 2,6-xylenol.
(Preparation of an Arylcoumaran Derivative)
[0106] In order to obtain an arylcoumaran derivative from a
lignophenol derivative, a lignophenol derivative having a carbon in
an ortho position relative to the phenolic hydroxyl group of the
aforementioned predetermined lignophenol derivative, i.e. a phenol
derivative is bound to the carbon at a sidechain .alpha.-position
of the main lignin structure, is treated under alkali
conditions.
[0107] This alkali treatment step dissociates a phenolic hydroxyl
group of the phenol derivative that was introduced at the sidechain
.alpha.-position, forming a bond with the sidechain
.beta.-positional carbon and at the same time, cleaves the
.beta.-aryl ether linkage. By this treatment, a coumaran structure
represented by the structural formula below can be formed at the
sidechain .alpha.-position. This treatment leads to etherification
of the phenolic hydroxyl group of the introduced phenol derivative
by formation of a bond between the phenolic hydroxyl group and the
carbon of the introduced phenol derivative, and the appearance of a
new phenolic hydroxyl group at a benzene ring of a main lignin
structure. As a result, this alkali treatment also transfers a
phenolic hydroxyl group (phenol activity) from an
.alpha.-position-introduced phenol derivative to the main lignin
structure.
[0108] More particularly, this alkali treatment is performed by
dissolving a lignophenol derivative in an alkali solution,
permitting the reaction to proceed for a period of time and, if
needed, heating.
[0109] Alkali solutions used in this treatment may be any alkali
solution as long as it can dissociate the phenolic hydroxyl group
of the introduced phenol derivative in the lignophenol derivative,
and the type and concentration of alkali conditions or the type of
solvents and the like are not limited, because when the
aforementioned dissociation of the phenolic hydroxyl group occurs
under alkali conditions, a coumaran structure is formed by the
adjacent groups.
[0110] For example, in the case of a lignophenol derivative in
which p-cresol is introduced, an aqueous NaOH solution can be used.
If treatment is performed at an alkali concentration of 0.5 to 2N
for 2 hours, it has been confirmed that the degree of low-molecular
species and the formation of arylcoumaran derivatives from the
lignophenol derivative are slightly different depending upon the
concentration of the alkali solution.
[0111] In addition, the lignophenol derivative will readily
rearrange under alkali conditions and heating to form a coumaran
structure. Conditions such as a temperature, pressure and the like
when the heating is started can be set without particular
limitation in a range for which the formation of an arylcoumaran
derivative is not promoted. For example, an arylcoumaran derivative
can be efficiently obtained by heating an alkali solution to a
temperature of not lower than 100.degree. C. In addition, an
arylcoumaran derivative may be obtained more efficiently by heating
an alkali solution to a temperature not lower than the boiling
point thereof under pressure.
[0112] It has been proved that, if the heating temperature is
increased, the production of low-molecular species by cleavage of
the .beta.-aryl ether linkage is promoted in the heating
temperature range of 120.degree. C. to 140.degree. C. for identical
alkali solutions and concentrations. In addition, it has been also
proved that, as the heating temperature is increased, phenolic
hydroxyl groups derived from an aromatic ring derived from the main
lignin structure are increased and phenolic hydroxyl groups derived
from an introduced phenol derivative are decreased, in the
aforementioned temperature range. Therefore, the degree of low
molecular species formation and the degree of transference of a
phenolic hydroxyl group site from an .alpha.-position-introduced
phenol derivative side to a phenol ring of the main lignin
structure can be adjusted by the reaction temperature. That is, in
order to promote low molecular species formation and obtain an
arylcoumaran derivative in which more phenolic hydroxyl group sites
are transferred from an .alpha.-position-introduced phenol
derivative side to the main lignin structure, a higher reaction
temperature is preferable. The heating temperature is preferably
not lower than 80.degree. C. and not higher than 160.degree. C.
When the temperature is much lower than 80.degree. C., the reaction
does not proceed sufficiently and, when the temperature
significantly exceeds 160.degree. C., non-preferable reactions
result. More preferably, the temperature is not lower than
100.degree. C. and not higher than 140.degree. C. In addition,
heating is preferably performed under pressure.
[0113] One example of such a treatment utilizes conditions under
which an aqueous 0.5N NaOH solution is used as the alkali solution
and the treatment is performed at 140.degree. C. for 60 minutes in
an autoclave. In particular, these treatment conditions are
preferably used for lignophenol derivatives that are derivatized
with p-cresol.
[0114] In low molecular species formation treatment of a
ligno-hybrid derivative in the alkali solution, for example, the
reaction is stopped by cooling or the like, the pH is lowered to
around 2 using a suitable acid, such as 1N hydrochloric acid or the
like, to regenerate the phenolic hydroxyl group (as an OH group),
and the resulting precipitates are centrifuged, washed under
neutral conditions and after lyophilization, further dried over
phosphorus pentaoxide. As a result, an arylcoumaran derivative,
i.e., a lignin-derived derivative having a coumaran skeleton, can
be obtained.
[0115] An arylcoumaran derivative is a lignin derivative containing
a structure (an arylcoumaran unit) in which a phenol ring is
introduced at a sidechain .alpha.-positional carbon atom of an
aromatic ring of a phenylpropane unit of lignin together with the
phenylpropane unit and forms a coumaran skeleton as shown in FIG.
17. The weight-average molecular weight is preferably 500 to 2000.
In addition, an arylcoumaran derivative having an arylcoumaran unit
of 0.3 to 0.5 mol/C9 (fundamental unit) is preferable. An
arylcoumaran derivative means both a monomer consisting of such an
arylcoumaran unit and a polymer partially having a fundamental unit
having an arylcoumaran unit (at least at an end part), including an
arylcoumaran derivative that is a mixture of the monomer and the
polymer. An arylcoumaran derivative may contain simple
low-molecular species compounds derived via the cleavages of the
benzyl aryl ether bond and .beta.-aryl ether bond of lignophenols
in the step for preparing this arylcoumaran derivative. Usually,
the arylcoumaran derivative is obtained in a mixed state in which
the mixture contains such low-molecularized compounds in addition
to a monomer and a polymer in the alkali solution.
[0116] FIG. 18 shows one example of an arylcoumaran unit obtained
from a lignophenol derivative using p-cresol as a phenol
derivative.
(Structure of an Arylcoumaran Derivative)
[0117] The percentage of the coumaran skeleton and the phenolic
aromatic ring in the thus obtained arylcoumaran derivative, the
amount of introduced cresol, the amount of a hydroxyl group and the
entire structure can be confirmed by a nucleus exchange method,
.sup.1H-NMR or the like.
[0118] A UV spectrum (solvent: tetrahydrofuran) and an IR spectrum
(KBr method) of an arylcoumaran derivative are shown in FIGS. 19
and 20.
(Preparation of a Lignin Cross-Linking Derivative)
[0119] A lignin cross-linking derivative refers to a derivative in
which a cross-linking functional group is introduced at an ortho-
and/or para-position relative to a phenolic hydroxyl group of a
lignophenol derivative. The weight-average molecular weight is
preferably 2000 to 10000 and the amount of introduced cross-linking
functional group is preferably 0.3 to 1.5 mol/C9 unit. A
hydroxymethyl group is preferable as the cross-linking functional
group.
[0120] A lignin cross-linking derivative can be obtained by mixing
a lignophenol derivative with a compound that can form a
cross-linking functional group on the lignophenol derivative to
react under conditions by which the phenolic hydroxyl group of the
lignophenol derivative will dissociate.
[0121] The conditions under which the phenolic hydroxyl group of
the lignophenol derivative will dissociate are usually formed in a
suitable alkali solution. The type and concentration of the alkali
conditions and the solvent can be used without limitation so is
long as the phenolic hydroxyl group of the hybrid compound
dissociates. For example, a 0.1N aqueous sodium hydroxide solution
can be used.
[0122] The cross-linking functional group that is introduced into
the lignophenol derivative is not particularly limited. Any
cross-linking functional group may be used so long as it can be
introduced at an aromatic ring of the main lignin structure or at
an aromatic ring of the introduced phenol derivative. More
particularly, the cross-linking reactive group can be introduced
into the aforementioned aromatic compound by mixing a polymerizable
compound, such as formaldehyde, glutaraldehyde, diisocyanate and
the like, with these compounds under conditions in which the
phenolic hydroxyl group in a lignophenol derivative can dissociate.
Because the .beta.-aryl ether linkage also dissociates under such
conditions, the lignophenol derivative is low-molecular
species.
[0123] Upon mixing of the lignophenol derivative with the
cross-linking functional group forming compound, in order to
efficiently introduce the cross-linking functional group, a
cross-linking functional group forming compound is preferably added
at 1 or more mole-amount with respect to the aromatic ring of the
lignin phenylpropane unit in the lignophenol derivative and/or the
introduced phenol ring. More preferably, it is added at 10 or more
mole-amount and, further preferably, 20 or more mole-amount.
[0124] Then, the cross-linking functional group is introduced into
the introduced phenol ring under conditions in which the phenol
derivative and the cross-linking functional group forming compound
are present in alkali solution, or by heating if necessary. While
the heating conditions are not particularly limited so long as a
cross-linking functional group is introduced, the range of
40.degree. C. to 100.degree. C. is preferable. When the temperature
is lower than 40.degree. C., the cross-linking functional group
forming compound reaction rate is very low and, when the
temperature is higher than 100.degree. C., side reactions result in
addition to the introduction of the cross-linking functional group
into the lignin, such as the cross-linking functional group forming
-compound reacting with itself. The range of 50.degree. C. to
80.degree. C. is more preferable and about 60.degree. C. is further
preferable.
[0125] The reaction is stopped by cooling the reaction solution and
acidifying with hydrochloric acid having a suitable concentration
(for example, around pH 2); the reaction mixture is washed and
dialyzed to remove the acid and unreacted cross-linking functional
group forming compound. After dialysis, the sample is recovered by
lyophilization or the like. If needed, the sample is dried over
phosphorus pentaoxide under reduced pressure.
(Structure of a Lignin Cross-Linking Derivative)
[0126] Whether the desired functional group has been introduced at
the o-position or p-position relative to the phenolic hydroxyl
group in the thus obtained lignin cross-linking derivative or not,
and the entire structure can be confirmed by a nucleus exchange
method, .sup.1H-NMR or the like.
[0127] A UV spectrum (solvent: tetrahydrofuran) and an IR spectrum
(KBr method) of an arylcoumaran derivative are shown in FIGS. 21
and 22.
[0128] In addition, in one example of structural conversion of
lignin, a lignophenol derivative, an arylcoumaran derivative and a
lignin cross-linking derivative are shown in FIG. 23. In this
example, p-cresol is used as a phenol derivative and a
hydroxymethyl group is introduced as the cross-linking functional
group.
(A Method for Confirming the Properties of the Lignophenol
Derivative, the Arylcoumaran Derivative and the Cross-Linking
Lignin Derivative)
[0129] 1. Confirmation of Production of a Coumaran Unit a
Quantification of the Distribution of the Phenolic Aromatic
Ring.
[0130] The structure of an arylcoumaran derivative, or more
particularly, the structure of an arylcoumaran fundamental unit,
can be confirmed by comparing, before and after the alkali
treatment, the frequency of the phenolic properties of the cresol
ring and the lignin aromatic ring (mainly guaiacyl ring) by a ring
conversion method combined with a periodate oxidation
treatment.
[0131] A nucleus exchange method is a procedure by which a phenol
monomer is quantitatively obtained from a phenol polymer, such as
lignin, in a medium in which boron trifluoride (BF.sub.3) and a
large excess of phenol are present. The reaction of lignin with
phenol in this nucleus exchange method introduces medium phenol at
a sidechain .alpha.-position of lignin side to form a
diphenylmethane type structure between a lignin aromatic ring and
to further liberate this lignin aromatic ring as guaialcohol or the
like and repeated DPM formation of the remaining introduced medium
phenol and liberation of a phenol ring. By utilizing the
quantitative properties of this reaction, the position at which the
phenyl ring is bound to an aliphatic sidechain in a phenylpropane
unit of lignin can be determined.
[0132] In addition, it is known that periodate treatment
quantitatively destroys the phenolic aromatic ring as shown in FIG.
25. When combined with the nucleus exchange method utilizing this
procedure, the distribution of hydroxyl groups in a lignin aromatic
ring and an .alpha.-position introduced phenol ring can be
analyzed.
[0133] A method for measuring the frequency of the phenolic
properties of the cresol ring and the guaiacyl ring and confirming
production of the coumaran unit by utilizing a nucleus exchange
method is provided below.
[0134] The following explanation provides one example for analyzing
the lignocresol exemplified in FIG. 23, which is one kind of a
lignophenol derivative using p-cresol as a phenol derivative, and
an arylcoumaran derivative shown in FIG. 26 that is obtained by
using this lignophenol as a starting material is explained. By
utilizing this analyzing example, the fundamental unit of other
arylcoumaran derivatives can be similarly confirmed. The symbols
shown in FIG. 26 represent the following structures:
Gp: Phenolic guaiacyl ring GE: Ether type guaiacyl ring CP:
Phenolic cresol ring introduced at an .alpha.-position CE: Ether
type cresol ring introduced at an .alpha.-position
[0135] As shown in FIG. 26, when this lignophenol is nucleus
exchange-treated, because cresol has a cresol ring at an
.alpha.-position at high frequency, a DPM type structure is formed
between guaiacyl ring-cresol ring from initiation. Therefore, the
lignophenol is rapidly nucleus exchanged and, regardless of the
phenolic properties of the guaiacyl ring, the guaiacyl ring and the
cresol ring are liberated as a monomer. That is, cresol liberation
is of all CP origin and guaiacyl ring (guaialcohol and catechol)
liberation is of GP and GE origin.
[0136] However, when the periodate treatment is performed, because
cresol (CP) is all phenolic, the cresol ring is destroyed and, at
the same time, the phenolic guaiacyl ring is also destroyed. An
ether type guaiacyl ring (GE) remains and liberation by a nucleus
exchange method provides only the non-phenolic guaiacyl ring
(GE).
[0137] On the other hand, when an arylcoumaran derivative is
produced as a low-molecular species, this lignocresol is directly
nucleus exchange-treated by the alkali treatment and the same
number as that of the hybrid compound before the alkali treatment
of a guaiacyl ring and a cresol ring are liberated. When this
low-molecular species compound is nucleus exchange-treated after
the periodate treatment, only an ethereal cresol ring (CE) forming
an arylcoumaran structure is liberated.
[0138] Therefore, whether .alpha.-position-introduced cresol is
bound to the .beta.-carbon in the alkali treatment or not (whether
a coumaran unit was formed or not) and whether the phenolic
properties were newly manifested in the guaiacyl ring or not, i.e.,
whether a coumaran structure was produced or not, can be confirmed
by the type of liberated phenols that are obtained by performing
the 4 kinds of nucleus exchange treatments, either alone, and
either before and after the alkali treatment, and the periodate
oxidation decomposition and the treatment combined with nucleus
exchange and by the difference in yields thereof.
[0139] More particular procedures are indicated below.
(Preparation of a Lignophenol Derivative Sample and an Arylcoumaran
Derivative Sample)
[0140] Each sample used for the nucleus exchange treatment and the
periodate treatment was prepared as follows:
[0141] The lignophenol derivative sample was prepared as follows:
After p-cresol was adsorbed onto wood powder, 72% sulfuric acid was
added to treat at room temperature for 60 minutes, all the reaction
solution was placed into an excess of water and the insoluble
fractions were collected by centrifugation, dialyzed and dried. The
dried material was extracted with acetone, the soluble fraction was
added dropwise to an excess of ethyl ether, and the resulting
insoluble fraction was dried on P.sub.2O.sub.5.
[0142] An arylcoumaran derivative sample was prepared by treating
the lignophenol derivative (lignocresol) obtained as described
above in a 0.5N aqueous NaOH solution at 140.degree. C. for 60
minutes, acidifying to pH 2 with 1N hydrochloric acid, washing the
precipitates under neutral conditions, lyophilizing and drying on
P.sub.2O.sub.5.
(Preparation of a Nucleus Exchange Reagent)
[0143] The reagent used for the nucleus exchange treatment was a
mixture of phenol (Nakalai Tesque, Inc., extra pure reagent),
xylene (Nakalai Tesque, Inc., extra pure reagent) and boron
trifluoride-phenol complex (contained at 25%, Nakalai Tesque, Inc.,
extra pure reagent) at a volume ratio of 19:10:3.
(Nucleus Exchange Treatment)
[0144] A suitable amount of a lignophenol derivative or an
arylcoumaran derivative sample was placed into a 3 ml stainless
steel microautoclave already containing two steel balls for
stirring, and 2 ml of a nucleus exchange reagent was added thereto.
The autoclave was sealed and stirred for 10 minutes or more to
homogenize the contents. Thereafter, the autoclave was immersed
into an oil bath at 110.degree. C. and heated for 4 hours. During
heating, the contents in the autoclave were stirred every 30
minutes.
[0145] After completion of the reaction, the autoclave was taken
out of the oil bath, placed into water, and the reaction was
stopped by cooling. Silicone oil adhered to the autoclave was wiped
completely clean, the autoclave was opened, and the contents were
transferred into a 100 ml beaker by washing with a small amount of
diethyl ether (Wako Pure Chemical Industries Co., Ltd., extra pure
reagent). A solution of a known amount of an internal standard
substance (dibenzyl (Tokyokasei Kogyo Co., Ltd. extra pure
reagent)) in benzene (Wako. Pure Chemical Industries Co., Ltd.,
extra pure reagent) (12 mg/ml) was added thereto, the
ether-insoluble was filtered with a glass fiber filter (Whatman
GF/A 4.5 cm) and washed a few times with diethyl ether. The
filtered material was transferred to a 300 ml separating funnel and
a saturated sodium chloride solution and sodium chloride (Nakalai
Tesque, Inc., extra pure reagent) were added with vigorous shaking
to inactivate the BF.sub.3. The ether layer was recovered and
concentrated to about 10 ml relative to 1 ml of a reagent. The
concentrated material was transferred into a 50 ml Teflon-liner
screw vial, anhydrous sodium sulfate (Wako Pure Chemical Industries
Co., Ltd., extra pure reagent) was added and dehydrated overnight
in a cool place.
(Quantification of Product)
[0146] 50 .mu.l, of the dehydrated ether solution was placed into a
1 ml Teflon-liner screw vial, one droplet of pyridine (Wako Pure
Chemical Industries Co., Ltd., extra pure reagent) and 100 .mu.l of
Bis (trimethylsilyl) trifluoroacetamide, BSTFA (Aldrich, 99+%) were
added thereto, and allowed to stand at room temperature for 1 hour
to perform the TMS treatment. A TMS derivative of a liberated
monomer was quantified by gas chromatography (GLC). The produced
amount was calculated from a calibration curve for a monomer. The
GLC conditions were as follows: [0147] Apparatus: YANAGIMOTO G-3800
[0148] Column: Crosslinked methyl silicon capillary column
(Quardrex s2006:0.25 mm I.D. 50 m length 0.25 .mu.m Film thickness)
[0149] Sensitivity: 10-1 [0150] Attenuator: 1/1 [0151] Column
temp.: Initial temp.: 130.degree. C., 6 min. [0152] :Rate:
3.0.degree. C./min. [0153] :Final temp.: 190.degree. C. [0154]
Injection temp.: 230.degree. C. [0155] Carrier gas: Helium [0156]
Detector: FID
(Preparation of a Periodate Oxidizing Reagent)
[0157] 500 ml of a solution of glacial acetic acid (Wako Pure
Chemical Industries Co., Ltd., extra pure reagent): water (3:2
(v/v)) was added to 15 g of sodium methaperiodate (Nakalai Tesque
Inc, extra pure reagent). The periodate oxidizing reagent was
placed in a brown reagent bottle and stored at 4.degree. C.
(Periodate Oxidation Treatment)
[0158] 1 ml of glacial acid was added to 100 mg of a lignophenol
derivative or an arylcoumaran derivative sample to dissolve the
sample as soon as possible, and 15 ml of a periodate oxidizing
reagent was added with stirring to perform the treatment at
4.degree. C. for 3 days. After treatment, the mixture was added
dropwise into 200 ml of ice-cooled water under stirring, the
resulting precipitates were centrifuged (5.degree. C., 3500 rpm, 10
min.) to recover the precipitates, washed with cool water, and
lyophilized to dry over P.sub.2O.sub.5 in order to obtain the
periodate oxidation treatment sample. This sample was nucleus
exchange-treated as described above, and subsequently the product
was quantified according to the aforementioned product quantifying
method. [0159] 2. Quantification of the Amount of Introduced Cresol
and Hydroxyl Group
[0160] Quantification of the amount of introduced cresol and
hydroxyl group was analyzed by .sup.1H-NMR.
[0161] The hybrid compound and the arylcoumaran derivative were
prepared as samples as is or as an acetylated material.
[0162] Each 20 mg of the sample and 3 mg of p-nitrobenzaldehyde
(PNB) as an internal standard were weighed precisely into a 1 ml
vial, which was completely dissolved in deuterated
pyridine:deuterated chloroform (1:3) (an acetylation sample was
dissolved only with deuterated chloroform) using an Eppendorf
pipette to obtain a sample for measurement.
[0163] Measurement by .sup.1H-NMR was performed using an R-90H
Fourier transformation type nuclear magnetic resonance apparatus
manufactured by HITACHI. From the integrated curve of the resulting
chart, the amount of introduced cresol was calculated according to
the following calculating method.
(Analysis)
[0164] The following is an example of an analysis that can be
applied to the lignocresol produced using cresol as a phenol
derivative, an arylcoumaran derivative produced by further treating
this lignocresol and a cross-linking lignin derivative.
[0165] (1) Quantification of the Amount of Introduced Cresol
[0166] .sup.1H-NMR was performed using the HITACHI R-90H Fourier
transformation type nuclear magnetic resonance apparatus. From the
integrated curve for the resulting chart, the amount of introduced
cresol was obtained according to the following calculating
method.
I wt
%={Pwt/Pm.times.Pn/Pi.times.Ci/Cn.times.(Cm-1)}/Lwt.times.100
I mol/C9={Iwt %/(Cm-1)}/{(100-Iwt %)/Lm}
[0167] Wherein:
Iwt %: Amount of introduced cresol (wt %)
Pwt: Weight of PNB (mg)
[0168] Pn: Number of aromatic ring Hs in PNB (4) Pi: Integrated
value of an area indicating an aromatic ring 4H signal in PNB
(8.40-7.80 ppm) Ci: Integrated value of an area indicating a methyl
group 3H signal in introduced cresol (2.40-1.60 ppm) Cn: Number of
protons of a methyl group introduced cresol (3). Cm: Molecular
weight of introduced cresol (108) Lwt: Weight of lignocresol
(hybrid derivative) (mg) I mol/C9: Amount of introduced cresol
(mol/C9) Lm: Molecular weight of 1 unit of lignin (200) [0169] (2)
Quantification of the Amount of Hydroxyl Group
[0170] Measurement of .sup.1H-NMR was performed using the same
apparatus as the aforementioned apparatus based on the same sample
preparing method. From the integrated curve for the resulting
chart, the amount of a phenolic hydroxyl group and that of an
aliphatic hydroxyl group were calculated according to the following
calculating method.
[0171] Because the .sup.1H-NMR spectrum for an acetylated sample
has an area indicating a phenolic acetoxyl proton signal (2.40-2.03
ppm) and an area indicating an aliphatic acetoxyl proton signal
(2.03-1.60 ppm) that overlap with an area indicating a methyl
proton signal of that introduced cresol (2.40-1.60 ppm), each
integrated value was corrected according to the following
equations:
Aph=Aph'-Oph.times.Aar/Oar
Aali=Aali'-Oali.times.Aar/Oar
Aph: An integrated value for an area indicating a phenolic acetoxyl
proton signal (corrected value) Aph': An integrated value for an
area indicating a phenolic acetoxyl proton signal in an acetylated
sample (corrected value) Oph: An integrated value for an area
(2.40-2.03 ppm) that overlaps with the phenolic acetoxyl proton of
an acetylated sample in the original sample Aar: An integrated
value for an area indicating an aromatic proton signal (7.80-6.30
ppm) in the acetylated sample Oar: An integrated value for an area
indicating an aromatic proton signal (7.80-6.30 ppm) in the
original sample Aali: An integrated value for an area indicating an
aliphatic actoxyl proton signal (corrected value) Aali': An
integrated value for an area indicating an aliphatic acetoxyl
proton signal (2.03-1.60 ppm) in the acetylated sample Oali: An
integrated value for an area (2.03-1.60 ppm) that overlaps with the
phenolic acetoxyl proton of the acetylated sample in the original
sample
[0172] The amount of hydroxyl group was calculated based upon these
corrected values:
phOHwt
%=(Pwt/Pm.times.Pn/Pi.times.Aph/An.times.OHm)/[Alwt-{Pwt/Pm.times-
.Pn/Pi.times.(Aph+Aali)/An.times.Acm-1)}]100
aliOHwt
%=(Pwt/Pm.times.Pn/Pi.times.Aali/an.times.OHm)/[ALwt-{(Pwt/Pm.ti-
mes.Pn/Pi.times.(Aali+Aph)/An.times.Acm-1)}].times.100
phOHmol/C9)=(phOHwt %/OHm)/{(100-Iwt %)/Lm}
aliOHmol/C9)=(aliOHwt %/OHm)/{(100-Iwt %)/Lm}
phOHwt %: the amount of a phenolic hydroxyl group (wt %)
Pwt: Weight of PNB (mg)
[0173] Pm: Molecular weight of PNB (151) Pn: Number of aromatic
ring Hs in PNB (4) Pi: Integrated value for an area indicating an
aromatic ring 4H signal (8.40-7.80 ppm) in PNB Aph: Integrated
value for an area showing a signal of phenolic acetoxyl proton
(corrected value) An: Proton number of a methyl group in an
acetoxyl group (3) OHm: Mass number of a hydroxyl group (17) ALwt:
Weight of acetylated lignin (mg) Aali: Integrated value for an area
showing a signal of aliphatic acetoxyl proton (corrected value)
Acm: Mass number of an acetoxyl group (43) phOHmol/C9: Amount of
phenolic hydroxyl group (mol/C9) Iwt %: Amount of introduced cresol
(wt %) Lm: Molecular weight of 1 unit of lignin (200) aliOHwt %:
Amount of an aliphatic hydroxyl group (wt %) aliOHmol/C9: Amount of
an aliphatic hydroxyl group (mol/C9) [0174] 3. Quantification of a
Hydroxymethyl Group of a Lignin Cross-Linking Derivative
[0175] An example is explained below in which formaldehyde was used
as a cross-linking functional group forming compound and a
hydroxymethyl group was introduced as a cross-linking functional
group. Also in the case where the other functional group was
introduced, a structure can be determined similarly. Formaldehyde
was calculated according to the following equation on the
assumption that formaldehyde is all introduced as a hydroxymethyl
group. [0176] HMwt % :Weight of hydroxymethyl (wt %)
Pwt: Weight of PNB (mg)
[0177] Pm: Molecular weight of PMB (151) Pn: Number of aromatic
ring H in PNB (4) Pi: Integrated value for an area showing an
aromatic ring 4H signal (8.40-7.80 ppm) in PNsB Mi: Integrated
value for an area showing a methylene signal (--CH.sub.2--OAc) in a
hydroxymethyl group (5.20-4.70 ppm) Mn: Proton number of a
hydroxymethyl group (2) HMm: Mass number of a hydroxymethyl group
(31) Aph: Integrated value for an area showing a signal of phenolic
acetoxyl proton (corrected value) Aali: Integrated value for an
area showing a signal of aliphatic acetoxyl proton (corrected
value) An: Proton number of a methyl group in an acetoxyl group (3)
ALwt: Weight of acetylated lignin (mg) Acm: Mass number of an
acetoxyl group (43) HMmol/C9: Amount of a hydroxymethyl group
(mol/C9) Iwt %: Amount of introduced cresol (wt %) Lm: Molecular
weight of 1 unit of lignin (200)
HMwt
%=(Pwt/Pm.times.Pn/Pi.times.Mi/Mn.times.HMm)/[ALwt-[Pwt/Pm.times.Pn/P-
i.times.(Aph+Aali)/An.times.(Acm-1)]}].times.100
HMmol/C9=(HMwt %/HMm)/[{(100-(Iwt %+HMwt %)}/Lm)
[0178] 4. Average Molecular Weight
[0179] Measurement of average molecular weight in a lignophenol
derivative, an arylcoumaran derivative and a lignin cross-linking
derivative was performed by gel permeation chromatography. A sample
for measurement was prepared by placing about 2 ml of distilled and
degassed tetrahydrofuran (THF) (manufactured by Wako Pure Chemical
Industries., Ltd., extra pure reagent) and each 1 mg of derivative
in a test tube, stirring with a touch mixer to dissolve completely,
adding one droplet of an about 4% p-cresol solution in THF as an
internal standard substance to make completely uniform and
filtering with a COSMONICE Filter "S". The measuring conditions
were as follows:
Column: Shodex KF802 and KF804
Solvent: THF
[0180] Flow rate: 1 ml/min:
Detector: UV (280 nm)
Range: 0.32
[0181] Amount of sample: 50 .mu.l
[0182] A calibration curve was made using a Polystyrene standard
(Mw: 390000, 233000, 100000, 25000, 9000, 4000, 2200, 760);
bisphenol A and p-cresol provided that molecular weight of
polystyrene was multiplied by a ratio of Q factor (0.5327) taking
the molecular form of a hybrid derivative and an arylcoumaran
derivative as well as polystyrene into consideration. The
weight-average molecular weight (Mw), number-average molecular
weight (Mn) of each sample were calculated according to the
following equations and a variance ratio (Mw/Mn) was also
calculated.
Mw=.SIGMA.(Hi.times.Mi)/.SIGMA.Hi
Mn=.SIGMA.Hi/.SIGMA.(Hi/Mi) [0183] wherein Hi is the Height of
chromatogram read every 0.5 ml Mi: Molecular weight read from the
calibration curve every 0.5 ml (Material for Molded Product Other
than the Arylcoumaran Derivative and the Lignin Cross-Linking
Derivative)
[0184] As molding materials that are used for manufacturing molded
products of the present invention, natural or synthetic fibrous,
chip-like or powdery materials are used as molding substrate
materials in addition to these lignin derivatives. The form of the
molding substrate material is not limited to these forms and
various forms can be widely used.
[0185] As fibrous molding substrate materials, various fibers such
as natural or synthetic various hydrocarbon fibers, metal fibers,
glass fibers, ceramic fibers, and fibers recycled from these fibers
can be used.
[0186] Among others, cellulose fibers are preferable because they
are readily available and reproducible. As the cellulose fiber,
mechanical pulp, chemical pulp, semichemical pulp and pulps
recycled from these pulps, as well as various artificial cellulose
fibers synthesized using these pulps as a raw material can be
used.
[0187] As a raw material for such the cellulose fiber, either
timber fiber using a coniferous tree and a broadleaf tree as a raw
material, or non-timber fiber such as paper mulberry, kenaf, Manila
hemp, straw and bagasse can be utilized.
[0188] In addition, cellulose fibers obtained by splitting various
products such as boards, newspapers and the like, which are pulp
processed products manufactured from a lignocellulose material,
also may be used.
[0189] As chip-like molding substrate materials, various materials
such as natural or synthetic various hydrocarbon, metal, glass,
ceramic and the like can be used. As hydrocarbon chips, natural
cellulose chips from timber or non-timber materials may be used. As
metal chips, alumina chips may be used. As ceramic chips, chips
such as Al.sub.2O.sub.3, SiO.sub.2 and the like may be used. From
the same reason as that for fibrous molding substrate materials,
cellulose chips are preferable.
[0190] As powdery molding substrate materials, a molding material
which is made into a powder by grinding or is originally in powder
form and which is derived from the same material as that for the
aforementioned chip material can be used.
(Preparation of a Molded Product using an Arylcoumaran Derivative
and/or a Lignin Cross-Linking Derivative)
[0191] In order to prepare a molded product, only an arylcoumaran
derivative can be used, or only a lignin cross-linking derivative
can be used, or both the arylcoumaran derivative and the lignin
cross-linking derivative can be used.
[0192] In order to prepare a molded product using an arylcoumaran
derivative and/or a lignin cross-linking derivative (hereinafter
referred to as secondary derivative or the like), a secondary
derivative or the like, which is in melted state or a solvent
dissolved state (hereinafter this state is referred to as liquefied
state), is added to a molding substrate material and a secondary
derivative or the like in this liquefied state and is
solidified.
[0193] The secondary derivative or the like exhibits caking
properties when it changes from the liquefied state into a solid.
That is, when it precipitates into a solid by distilling the
solvent off from the liquefied state, or when it solidifies from a
melted state by cooling, the adhesive properties and the caking
properties are exhibited. By utilizing such a caking property
exhibiting process, the secondary derivative or the like can be
used as a binder for mutually adhering molding substrate
materials.
[0194] Therefore, upon preparation of the molded product, the
secondary derivative or the like is usually passed through a
process in which a secondary derivative or the like in a solution
state is added to the molding material and is liquefied and
thereafter, the solvent is distilled off, or a process in which a
secondary derivative or the like in the solid state is added,
heated to melt and liquefy and then cooled.
[0195] The secondary derivative or the like solution used herein is
a liquid in the state in which the secondary derivative or the like
is dissolved in a solvent. As a solvent used for this derivative
solution, acetone, ethanol, methanol, dioxane, tetrahydrofuran, or
a mixture of each of them with water can be used. In addition, a
secondary derivative or the like solution obtained in a step for
synthesizing and separating a secondary derivative or the like from
a lignocellulose material may be also used.
[0196] For example, as a method for preparing a molded product, a
method comprising steps shown FIGS. 27 to 31 is provided.
[0197] As shown in FIG. 27, a cellulose fiber is molded, and this
molded product is impregnated with a secondary derivative or the
like solution and a solvent is distilled off. By removal of a
solvent by distillation, the secondary derivative or the like
provides caking properties and adhesive properties to molding
materials. As a result, the secondary derivative or the like is
attached to the cellulose fiber to obtain a molded product in the
state in which the -secondary derivative or the like acts as a
binder. If needed, this molded product may be further molded by
pressurizing and/or heating.
[0198] Alternatively, as shown in FIG. 28, a cellulose fiber is
molded, and the molded product is impregnated with a secondary
derivative or the like solution. Thereafter, the solvent is
distilled off by pressurizing and/or simultaneously heating this
molded product. By removal of the solvent by distillation, a
secondary derivative or the like provides caking properties and
adhesive properties to molding materials. As a result, a
lignophenol molded product in the state in which a secondary
derivative or the like acts as a binder can be obtained.
[0199] According to methods shown in FIGS. 27 and 28, a secondary
derivative or the like is transferred to the surface layer side in
the solvent distillation step. FIG. 29 shows transference to the
surface layer exemplified with an arylcoumaran derivative. That is,
a large amount of secondary derivative or the like is attached to
the surface layer of the molded product. Therefore, because a large
amount of secondary derivative or the like is present on the
surface layer side by attaching a relatively small amount of the
secondary derivative or the like, a molded product having
water-resistance and strength can be obtained by the binding action
of the secondary derivative or the like on the surface layer
side.
[0200] In this case, particularly when a highly hydrophobic
arylcoumaran is used, i.e., an arylcoumaran derivative synthesized
from a lignophenol derivative with cresol, a highly hydrophobic
molded product can be efficiently obtained.
[0201] Further, as shown in FIG. 30, after cellulose fiber in the
unmolded state is impregnated with the secondary derivative or the
like, the solvent is distilled off. Thereafter, this fiber is
molded by heating and/or pressurizing.
[0202] According to this method, a secondary derivative or the like
is attached to a fiber in advance using the adhesive properties by
distilling the solvent off. As such, by molding with heating and
pressurization using a fiber to which a secondary derivative or the
like is attached in the solid state in advance, a molded product in
which a secondary derivative or the like is uniformly distributed
throughout the product can be molded via from the liquid state to
the solid state. Therefore, this method is preferable as a process
for preparing a molded product having uniform properties.
[0203] Further, as shown in FIG. 31, a powdery secondary derivative
or the like is mixed into a cellulose fiber and molded by heating
and/or pressurizing. Alternatively, prior to the final molding, a
provisional molding step can be performed by pressurizing.
Thereafter, such provisionally molded product is heated to mold
and, if necessary, pressurized. According to this method, the
solvent distillation step becomes unnecessary. In addition, a
molded product in which a secondary derivative or the like is
uniformly distributed throughout the product can be formed and
thus, a molded product having uniform physical properties can be
manufactured.
[0204] In addition, upon preparation of the molded product from
various molding materials and a secondary derivative or the like,
provisional molding before molding or a molding method can be
variously selected and added and further other additional steps may
be added. For example, when a fibrous pulp is used as the molding
material, a wet process or a dry process for forming a molded
product and a provisional molding method and the like may be used
and are different processes.
(Preparation of a Molding Product using a Lignin Cross-Linking
Derivative)
[0205] In a molded product using a lignin cross-linking derivative,
the molding substrate can be strengthened by cross-linking and
heating the molding substrate material to which the linking
cross-linking derivative is attached. Heating may be accompanied
with pressurizing. Formation of cross-links is also possible by
heating when distilling the solvent off from the molding substrate
material to which a cross-linking derivative in the liquid state is
attached.
[0206] In the case of a molded product in which cross-linking of a
cross-linking derivative was performed, the hydrophobicity is
improved and, in particular, the strength is improved.
(Recovery of an Arylcoumaran Derivative from an Molded Product)
[0207] Further, as shown in FIG. 32, by adding again a solvent to
the present molded product, the product can be separated into
fibers and an arylcoumaran derivative, which can be recovered.
[0208] The arylcoumaran derivative is extracted from the molded
product using a solvent having affinity for the arylcoumaran
derivative (hereinafter referred to as the present solvent).
[0209] In this case, the present solvent may be acetone, ethanol,
methanol, dioxane, tetrahydrofuran, a mixture of one of these
solvents and water, or an aqueous alkali solution and the like.
Considering simplicity, acetone and alcohol are preferable. In
addition, considering the cost, an aqueous alkali solution is
preferable.
[0210] More particularly, during the recovery of the arylcoumaran
derivative, whether the original shape of the molded product is
maintained or the molded product is processed into small pieces,
the molded product or the small pieces are dipped into a solvent
having affinity for the arylcoumaran derivative and further
stirred. As a result, the arylcoumaran derivative is extracted into
the solvent. By processing the molded product into small pieces and
stirring into the solvent, rapid separation and extraction become
possible. Alternatively, when the original shape of the molded
product is desired to be maintained, the arylcoumaran derivative is
dipped into a solvent having affinity for the arylcoumaran
derivative, but the solvent is non-aqueous (for example, acetone)
and allowed to stand to extract without stirring. In particular, in
the case of a molding substrate material using a cellulose system,
when the arylcoumaran derivative is intended to be extracted and,
at the same time, the molded product is intended to be separated
into molding materials by splitting or the like, the molded product
is dipped into an aqueous alkali solution and stirred.
[0211] As such, the recovered arylcoumaran derivative can be
utilized again in various fields in addition to preparation of
molded products. In addition, molding substrate materials that were
separated at the same time can be utilized again in various fields
in addition to preparation of molded products.
(Recovery of a Lignin Cross-Linking Derivative from a Molded
Product)
[0212] In addition, when the molded product is prepared by heating
without cross-linking, the lignin cross-linking derivative can be
recovered from the molded product using a solvent having affinity
for the lignin cross-linking derivative, as was the case for the
arylcoumaran derivative. Solvent having affinity for the lignin
cross-linking derivative are acetone, ethanol, methanol, dioxane,
tetrahydrofuran, a mixture of one of these solvents and water, or
an aqueous alkali solution and the like. Considering simplicity,
acetone and alcohol are preferable. In addition, considering the
cost, an aqueous alkali solution is preferable.
[0213] According to the present invention, a lignophenol derivative
is obtained from various lignocellulose materials via a phase
separating process with a phenol derivative and concentrated acid
and this derivative is further secondarily-derivatized to obtain an
arylcoumaran derivative or a lignin cross-linking derivative that
can be complexed with various fibers to prepare a molded product.
The derivative and the fiber material in the molded product are
separated from the molded product. Therefore, by using an
arylcoumaran derivative and a cross-linking derivative as a
material for molding, preparation of the molded product and
separation can be repeatedly performed. Therefore, a lignocellulose
can be efficiently reused.
[0214] Arylcoumaran derivatives produced according to the present
invention can be used as an ultraviolet absorber or a lignin
material having low protein absorbing properties.
[0215] Lignin cross-linking derivative s produced according to the
present invention can be used as a switching element, a hydrophilic
high protein absorber, an ultraviolet absorber or the like.
EXAMPLES
[0216] The following Examples illustrate the present invention. In
the following Examples, preparation of a molded product of a
cellulose fiber using an arylcoumaran derivative and a lignin
cross-linking derivative, and recovery of each derivative from a
molded product are explained. The steps of Examples 1 to 3 are
shown in FIG. 33.
Example 1
Synthesis of a Lignophenol Derivative
[0217] Lignocresol as a lignophenol derivative was synthesized
using Pinus Thunbergii as the lignocellulose material according to
the following steps. That is, to Pinus Thunbergii defatted wood
powder was added an acetone solution containing about 3
mole-amounts per lignin C.sub.9 unit in the Pinus Thunbergii
defatted wood powder and the mixture was well stirred and allowed
to stand overnight to impregnate the wood powder with p-cresol.
Thereafter, the wood powder was thinly spread in a vat and allowed
to stand in a draft until the acetone odor is lost due to
distillation of the acetone. The amount of C.sub.9 unit in the
lignin in the Pinus Thunbergii defatted wood powder was calculated
based on elementary analysis of the lignin in the Pinus Thunbergii
defatted wood powder.
[0218] Then, 250 g of wood powder with p-cresol adsorbed thereon
was placed into a beaker, and 1200 ml of 72% sulfuric acid was
added thereto while stirring with a glass bar. After stirred for
about 10 minutes, the mixture was further stirred with a stirrer
for 1 hour and thereafter, the reaction was stopped by the addition
of 10 L of water. After allowing it to stand for a few days, the
precipitate fraction was deacidified by dialysis. After the
precipitate was dried in a drier at 40.degree. C. for a few days,
the lignophenol derivative fraction was extracted with acetone, the
acetone fraction was added dropwise to a large excess of
benzene:hexane (2:1) (v/v) while stirring, and the produced
precipitate was washed with ethyl ether. Afterwards, the
precipitate was dried at room temperature and atmospheric pressure,
and dried over phosphorus pentaoxide under reduced pressure to
obtain the lignophenol derivative (lignocresol).
[0219] The molecular weight, the amount of introduced cresol, the
hydroxyl group distribution and the phenolic property frequency of
this lignophenol derivative are shown in FIGS. 34 and 35.
Example 2
Synthesis of an Arylcoumaran Derivative
[0220] 4 g of the lignophenol derivative obtained in Example 1 was
dissolved in 80 ml of a 0.5N aqueous sodium hydroxide solution, was
placed into a stainless steel autoclave and heated at 140.degree.
C. for 6 hours and allowed to react. The reaction was stopped by
cooling, acidified to pH 2 with 1N hydrochloric acid, the produced
precipitate was collected by centrifuging, and washed to neutral.
The resulting precipitate was lyophilized and dried over phosphorus
pentaoxide under reduced pressure to obtain an arylcoumaran
derivative. The molecular weight, the amount of introduced cresol,
the hydroxyl group distribution and phenolic property frequency are
shown in FIGS. 34 and 35.
Example 3
Synthesis of a Lignin Cross-Linking Derivative
[0221] Lignocresol was obtained according to the same method as
that of Example 1. The molecular weight and the amount of
introduced cresol of this lignocresol are shown in FIG. 36.
[0222] 20 g of this lignophenol derivative was placed into
three-necked flask, was dissolved with 1.2 L of a 0.1N aqueous
sodium hydroxide solution, and 180 ml of a 37% formaldehyde
solution (corresponding to 20 mole-amount of formaldehyde relative
to introduced cresol and the main lignin structure aromatic ring)
was added, heated at 60.degree. C. for 3 hours to introduce the
cross-linking functional group. The reaction was stopped by
cooling, acidified to pH 2 with 5% hydrochloric acid and the whole
solution was transferred into a dialysis membrane, where the acid
and unreacted formaldehyde were removed. After dialysis, a sample
was recovered by lyophilizing and dried over phosphorus pentaoxide
under reduced pressure to obtain the lignin cross-linking
derivative. The molecular weight and the amount of introduced
cresol of this lignin cross-linking derivative are shown in FIG.
36. In addition, the hydroxyl group distribution and the amount of
hydroxymethyl thereof are shown in FIG. 37.
Example 4
Attachment of Various Derivatives to a Cellulose Fiber Mat
[0223] Regenerated paper was used as the cellulose material, was
dipped into water overnight, splitted well and thereafter, fibers
were aggregated using a cylinder having a diameter of about 10 cm.
Then, the aggregate was dehydrated and dried to prepare a mat
having a diameter of about 100 mm and a thickness of 9 mm.
[0224] A mat piece A, 20 mm.times.99 mm, for preparing sample for
the strength test, and a mat piece B, 20.times.20 mm, for preparing
a sample for the water absorbing test were cut and taken from this
fiber mat using a motor disc saw. [0225] (1) Preparation of a Mat
for the Strength Test
[0226] The lignophenol derivative obtained in Example 1 or the
arylcoumaran derivative obtained in Example 2 was attached to this
mat piece A at a ratio of 5%, 10% or 20% by weight. In addition,
the lignin cross-linking derivative was attached to a mat piece A
at a rate of 15% by weight. That is, the aforementioned lignophenol
derivative, the arylcoumaran derivative or the lignin cross-linking
derivative was dissolved in acetone separately to prepare a
solution for attachment, and a predetermined amount of the
aforementioned solution for attachment was added separately so that
the lignophenol derivative or the arylcoumaran derivative was
attached to various mat pieces at a rate of 5%, 10% or 20%,
respectively, in a cylindrical stainless steel container having a
diameter of 10 cm. The lignin cross-linking derivative obtained in
Example 3 was attached to mat piece A at a ratio of 15%, which was
dipped in the solution overnight to allow the solution to
thoroughly permeate for attachment into mat piece A. Thereafter,
acetone was gradually evaporated while turning over mat piece A
every 1 hour, to attach various derivatives to mat piece A.
[0227] Mat piece A was removed from the container at the point in
time when the acetone appeared to completely evaporated from the
container based upon visual observation, the remaining acetone in
the interior of the mat was evaporated in a blast drier at
60.degree. C., and the weight was measured. The initial weight of a
mat was subtracted from the weight after attachment of the
derivative to calculate the amounts of various derivatives.
[0228] With regard to mat piece A having an attached cross-linking
derivative, after the cross-linking derivative was attached
thereto, heating treatment was performed at 170.degree. C. for 60
minutes to prepare a heat-treated material. [0229] (2) Preparation
of a Mat for the Water Absorbing Test
[0230] The lignophenol derivative obtained in Example 1 or the
arylcoumaran derivative obtained in Example 2 was attached to mat
piece B at a ratio of 5%, 10% or 20% by weight, respectively,
similar to the mat for the strength test. In addition, a lignin
cross-linking derivative was attached to a mat piece B at a ratio
of 20% by weight, similar to the mat for the strength test.
[0231] Moreover, mat pieces B with various derivatives attached
were heated at 170.degree. C. for 60 minutes to prepare
heat-treated materials, respectively (only heat-treated material
was prepared for the mat piece having the attached lignin
cross-linking derivative).
[0232] For comparison in assessment described below, a control mat
piece with nothing attached thereto was made according to the same
steps as those of this Example, except for the attaching step. Also
regarding the control mat piece, a heat-treated compound was
prepared by heating at 170.degree. C. for 60 minutes.
Example 5
Assessment
[0233] Various mats thus prepared were tested for the following
items.
Appearance
[0234] The various mat pieces were observed with the naked eye.
[0235] The various mat pieces turned brown as a whole, and
heat-treated materials made by heat-treating the mat pieces were
all uniformly and densely colored.
Mat Strength Test
[0236] Mat piece A for the strength test and the control mat piece
were tested using a span length of 80 mm and using the steel
apparatus shown in FIG. 38 for supporting the test piece and
providing a load. A concentrated load was applied to the entire
width of a span center from the surface of the test piece and the
average load rate was 2 mm/min.
[0237] According to this test apparatus and method, a
load-deflection curve was prepared and, from this curve, modulus of
elasticity (MOE) and modulus of rupture in bending (MOR) were
calculated. In addition, Pmax was calculated.
[0238] The results are shown in FIGS. 39 (a), 39 (b) and 39
(c).
[0239] From the results of FIGS. 39 (a), 39 (b) and 39 (c), the
arylcoumaran derivative was excellent for each of Pmax, modulus of
elasticity and modulus of rupture in bending as compared with the
lignophenol derivative. Therefore, it was seen that the molded
product with the arylcoumaran derivative attached thereto has the
increased strength as compared with the corresponding molded
product using the lignophenol derivative. In addition, it was seen
that the arylcoumaran derivative has improved function as a binder,
even when it was obtained by low-molecularizing the lignophenol
derivative.
[0240] Moreover, the molded product (heat-treated material) using
the cross-linking derivative had a much greater Pmax, modulus of
elasticity and modulus of rupture in bending than those of the
arylcoumaran derivative and it was seen that the strength can be
greatly improved.
Water Absorbing Test
[0241] A stainless steel net was placed on the bottom of a vat,
water was added so that the distance from the net bottom to the
surface of water was 3 cm and the temperature of water was
maintained at 25.degree. C. Mat piece B prepared for the water
absorbing test was immersed therein and a stainless steel net as a
weight was placed on the upper surface of mat piece B and allowed
to stand for 1 hour in order to maintain the upper surface of test
piece B at 3 cm under the surface of the water, so as not to
float.
[0242] After a predetermined period of time, the immersed mat piece
B was taken out, placed on a stainless steel net and after 10
minutes, the test piece was rapidly rolled onto a filer to remove
water droplets on the surface thereof, the weight and dimensions
were measured and a volumetric change rate relative to before
immersion in water was calculated. The results thereof are shown in
FIGS. 40 to 42.
[0243] In addition, mat piece B after immersion in water was
allowed to stand at 105.degree. C. for 15 hours in a drier,
removed, cooled, and the weight and dimensions thereof were
measured. A volumetric change rate of mat piece B after drying was
calculated and compared with the volumetric change rate after
immersion in water in order to assess the dimensional stability of
the molded product. The results are also shown in FIGS. 40 to
43.
[0244] As is apparent from the results of FIG. 40, the unheated
material of the heat-treated material of mat pieces B with a
lignophenol derivative attached thereto at various amounts
displayed a volumetric change rate of about 5 to 10% and after
drying, had a volumetric change rate of about -3 to 2%.
[0245] To the contrary, mat pieces B with an arylcoumaran
derivative attached thereto (unheated material and heat-treated
material) had a volumetric change rate of about 7 to 10% and after
drying, had about -1 to 1%. That is, although the volumetric change
rate after immersion in water was similar to that of the molded
product with the lignophenol derivative attached thereto and there
was no great difference, after re-drying, the volume was as great
as that before immersion in water (see FIG. 41). Therefore, the
dimensional stability of a mat piece B with an arylcoumaran
derivative attached thereto can be said to be better. In addition,
the amount of water absorption was almost same as that of the
lignophenol derivative.
[0246] In addition, although mat piece B with the cross-linking
derivative attached thereto had a volumetric change rate of about
7% after immersion in water, the volume returned back to nearly
that before immersion in water after re-drying and thus, it was
seen that mat piece B with the cross-linking derivative attached
thereto had better dimensional stability. With respect to water
absorption, mat piece B with the cross-linking derivative attached
thereto had about 60% of the water absorption of that of the mat
piece B with the arylcoumaran derivative attached thereto and that
of mat piece B with the lignophenol derivative attached thereto;
thus, it was seen that water-resistance was improved by
cross-linking (see FIG. 42, in this figure, comparison was
performed on a heated material of each derivative having an
attached amount of 20%).
[0247] From these results, it was clear that by attaching the
arylcoumaran derivative or the lignin cross-linking derivative
obtained by further secondarily-derivatizing lignocresol to a
molding substrate material, the water absorption of the mat was
reduced. As a result, dimensional stability with respect to
moisture was imparted thereto. In particular, this tendency was
remarkable in mat piece B with the lignin cross-linking derivative
attached thereto (heat-treated material).
Example 6
Test for Recovering Lignocresol from a Board
[0248] Mat piece B for the water absorption test with each of a
lignophenol derivative, an arylcoumaran derivative and a
cross-linking derivative was prepared according to Example 4, and
was used as a mat piece for the recovery test. With respect to the
material with the lignophenol derivative attached thereto and the
material with the arylcoumaran derivative attached thereto, a
non-heated material and a heat-treated material (170.degree. C., 60
min.) were prepared to obtain a mat piece for the recovery test
and, with respect to the lignin cross-linking derivative, a
heat-treated material (170.degree. C., 60 min.) was used as the mat
piece for the recovery test. The amount of each derivative to be
attached was 20% by weight per weight of the cellulose fiber in
every case.
[0249] These mats were immersed into about 30 ml of THF in a vial.
Afterwards, they were allowed to stand for 2 days without stirring,
the immersion solution was filtered, washed with THF, the filtrate
and the washing solution were combined, THF was distilled off, and
the resulting fraction was used as a recovery fraction. The results
are shown in FIG. 44.
[0250] As apparent from the results of FIG. 44, 100% of the
arylcoumaran derivative was recovered.
[0251] The better recovery rate is further effective in that the
arylcoumaran derivative does also not remain on one side of the
cellulose material. A trace of a lignin cross-linking derivative
was recovered due to its cross-linked structure.
[0252] In addition, in the case of the lignophenol derivative and
the arylcoumaran derivative, cellulose material was recovered in
the reusable state.
[0253] As such, according to the first invention and the fourth
invention, lignin that is a component of a lignocellulose complex
structure of a forest resource can be efficiently utilized and a
new functional material can be provided.
[0254] According to the fifth invention, a molded product can be
provided that can be easily incorporated into a molding substrate
material and can be again separated and reused together with a
molding substrate and a binder material.
[0255] According to the sixth invention, a molded product can be
provided that has water-resistance and strength.
[0256] According to the seventh invention, an arylcoumaran
derivative can be efficiently and repeatedly utilized and a molding
substrate material can be efficiently reused.
* * * * *