JP3522706B2 - WOOD BASE MATERIAL AND PROCESS FOR PRODUCING THE SAME - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an essential base material and a method for producing the same, and more specifically, to biodegradation with high strength by reconstructing a plant fiber material having high strength by a method having a low environmental load. The present invention relates to a wood-based base material having recyclability and recyclability, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, laminated wood materials, LVL (single board laminated wood), plywood, PB (particle board), FB (fiber board), etc. have been widely used as wood resource materials for construction materials (as board materials) and others. It is used as an industrial material (molding material, etc.).

Microscopically, wood is a composite material composed of cellulose, lignin, hemicellulose and the like. Cellulose crystals serve as the skeleton of the cell wall, and lignin and hemicellulose act as a matrix. And, due to the high crystallinity of cellulose and the secondary bond between the main components of cellulose, lignin and hemicellulose, it has high elasticity, very low plasticity and no meltability. The direct properties peculiar to wood are used as they are for the above woody resource materials.

On the other hand, as a wood-based resource material, there is pulp which is mainly used as a raw material for paper. Pulp is a monofilament of plant fibers such as wood, dust and leaves by chemical or mechanical methods, and is classified into mechanical pulp (MP), chemigrand pulp (CGP) and chemical pulp (CP). Further, the chemical pulp is classified into kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP), and they are used for applications making full use of their respective characteristics. Pulp is different from the above-mentioned wood resource material, and is used for applications in which the characteristics of using a material made into a single fiber are utilized.

[0005]

However, the woody resource materials such as the fiberboard mentioned above have the direct properties peculiar to the timber, which are utilized as they are. If you take the measure to make it into a shape, you will immediately have a problem in terms of strength.

Further, since the above-mentioned monofilament pulp is mainly used as a raw material for paper, reforming research for making the various performances that paper should have is often conducted. However, the present situation is that there has been little research on further modifying the paper to form a thin plate that exhibits high strength.

On the other hand, as a wood-based material, in recent years, a material called thermoplastic wood or heat-melting wood has been attracting attention. This seed material is produced by an esterification reaction or an ether reaction accompanied by amorphization of cellulose while simultaneously changing the secondary bond state between cellulose, lignin, and hemicellulose which are the main components of wood. The fact that the wood constituents can be treated as they are without being separated, and WPC (Wood Plastic Compo
sit, Wood Polymer Combinat
ionic) and other chemical treatments, it is essentially directed to materials that have lost the properties of wood. In terms of results,
Since it is a material that exhibits plasticity and heat melting properties, the use of new wood as an industrial raw material is expected.

However, as the production method thereof, as seen in the example of esterification of wood flour with higher fatty acid,
Considering environmental issues (safety, etc.), it is essential to use chemical treatment agents such as adding pyridine as a co-catalyst to N ₂ 0 ₄ -DMF (dimethylformamide) mixed solvent which is an amorphous solvent of cellulose. In this case, not only the manufacturing environment but also the product itself, there are some uncertainties about the development as a next-generation new material.

The present invention has been made in view of the above circumstances, and is a high-strength, biodegradable and recyclable product obtained by reconstructing a plant fiber material having high strength by a method having a small environmental load. It is an object of the present invention to provide a wood-based substrate having the same and a method for producing the same.

[0010]

Then, the inventors of the present invention pay attention to the point that "the wood constituent components are not separated" which is the principle of manufacturing the thermoplastic wood, and conversely, the wood constituent components are separated. Starting from the state described above, we thought that it would be possible to create a high-strength wood-based base material that is a thin plate-like body by rebuilding the separated constituents.As a result of intensive research, we started from the pulp fiber state. As a result, the wood base material according to the present invention has been created. Furthermore, in consideration of environmental problems, the manufacturing method has been developed without using any harmful chemical treating agent and by a mechanical method instead of chemical treatment.

Specifically, the invention according to claim 1 for achieving the above object is a pulp fiber aggregate which has been highly plasticized and fibrillated, wherein each pulp fiber is highly entangled and approached to each other. A wooden base material, characterized in that a strong bond is formed between them,
By increasing the number of bonding points per unit fiber and forming a strong bond, the bending performance such as bending strength and Young's modulus is remarkably improved. Specifically, a base material having a bending strength of about 150 MPa and a bending Young's modulus of about 13 GPa can be obtained.

Further, the invention according to claim 2 is a pulp fiber assembly which has been plasticized and fibrillated,
Furthermore, each pulp fiber is a wood-based substrate characterized by being strongly bonded through interfiber bonding components, by interfiber bonding components being interposed between each pulp fiber,
In addition to the direct bonding between the fibers, the bonding by the interfiber bonding component is added, and the bending strength and the bending Young's modulus are remarkably improved.

The invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the pulp fiber is a kraft pulp fiber. Here, the kraft pulp fiber has an advantage that plasticization can be relatively easily realized in the presence of water because the lignin component is extremely small among cellulose, lignin, and hemicellulose that are wood constituents. . In addition, the kraft pulp fiber has a very high tensile strength of about 1.0 GPa to 1.5 GPa and is advantageous for creating a high-strength wood-based substrate that is a thin plate. The tensile strength of steel is 0.4G
Since it is about Pa and the tensile strength of the carbon fiber is about 3 GPa, it can be said that the tensile strength of the kraft pulp fiber is very high.

Further, the invention according to claim 4 is the invention according to claim 2, wherein the interfiber bonding component is a natural adhesive agent. As the natural adhesive, for example, by using "starch glue" which is a polysaccharide, an effective binder having no problem of biodegradability can be obtained.

Further, the invention according to claim 5 is the method for producing a wood-based substrate according to the present invention, wherein a pulp sheet-like body made of pulp fibers is first impregnated with a sufficient amount of warm water. After that, a hot water impregnation dehydration step of removing excess water by dehydration is performed, and further, the pulp sheet-like material impregnated with hot water is subjected to a kneading step for kneading for a predetermined time with a kneader to perform a kneading step, and further, A predetermined amount of water is added to and mixed with the kneaded product to adjust the fluidity, and a fluidity adjusting step of obtaining a molding preparation is performed, and further, the molding preparation is put into a molding die and stored in the molding die. The molded preparation thus prepared is subjected to a dehydration step of dehydrating to a first water content by pressurizing,
Further, a drying step of drying the molding preparation adjusted to the first water content under pressure to obtain a preformed dried material adjusted to the second water content, and further performing the preforming The dried product is heated under the heating range of 120 ° C to 200 ° C and at 5M.
A wood material comprising a pulp fiber aggregate that has been plasticized and fibrillated by sequentially performing a heating and pressurizing and holding step of holding for a predetermined time under a predetermined plasticizing condition under a pressure range of Pa to 100 MPa. A method for producing a Kiga base material, which comprises producing a base material.
If the heating range of the dried preform is 200 ° C. or higher, heat deterioration of the pulp occurs and the strength of the formed product decreases, which is not preferable. Further, the pressurizing range varies depending on the temperature and the water content.

Further, the invention according to claim 6 is the method for producing a wood-based substrate, characterized in that in the fluidity adjusting step according to claim 5, an interfiber bonding component is further added. According to the above-described manufacturing method, sufficient hot water is spread to each part inside and outside the pulp sheet-like body in the hot water impregnation dehydration step, and the pulp sheet-like body made of the pulp fiber aggregate is sufficiently swollen as a whole. In the subsequent kneading process,
By sufficient kneading, the pulp fibers are highly fibrillated. A preformed dried product, which is a semi-finished product with stable quality, can be obtained through the subsequent fluidity adjusting step, dehydration step, and drying step. By performing the dehydration and drying under load, it is possible to reliably suppress the phenomenon that the molding preparation is warped. Further, by performing the heating and pressurizing and holding step, fluidization occurs in the pulp fiber aggregate under a high compression state, plasticization progresses, and a wood-based pulp fiber aggregate that has undergone plasticization and fibrillation progresses. A base material is created.

Further, as in the invention according to claim 6,
In the fluidity adjusting step according to claim 5, further
By adding the interfiber binding component, the interfiber binding component serving as the binder to be interposed between the pulp fibers can be easily and evenly arranged in the molding preparation, and the binding force between the pulp fibers is further strengthened. It Further, as in the invention according to the seventh aspect, if a kneader is used as a kneading machine in the kneading step, fibrillation of pulp fibers can be extremely effectively promoted.

[0018]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
A preferred embodiment of the present invention will be described in detail. FIG. 1 is a diagram schematically showing the chemical structure of a wood-based substrate 1 according to the present invention. FIG. 1a schematically shows the chemical bonding state without kneading with a kneader (A
1), and the fiber-to-fiber bond points 2 (indicated by a cross in the circle in the figure) are far more than those in other states (A2) and (A3) shown in FIGS. 1b and 1c. It will be understood that there are few. In addition, what is shown as a linear body is monofilament pulp 3.

FIG. 1b is a schematic view (A2) showing the chemical bonding state when kneading with a kneader.
It will be understood that a large number of interfiber bonding points 2 are formed as compared with the state shown in FIG. That is, it is speculated that the kneading with the kneader promoted the fibrillation of pulp fibers and significantly increased the bonding points.

FIG. 1c schematically shows a state in which the interfiber bonding component 4 is mixed in the state of FIG. 1b (A2) (A
3), and the inter-fiber bonding component 4 exerts its binding force across a plurality of single fiber pulps, so that the strength of the pulp fiber aggregate as a whole is further increased as compared with the state of FIG. 1b. The effect is demonstrated. The effect of kneading with a kneader will be described later with reference to the micrograph shown in FIG.

FIG. 2 is a manufacturing flow sheet showing the manufacturing process of the wood-based material according to the present invention. As shown in the figure,
First, the pulp sheet is impregnated in warm water (step S
1), followed by dehydration of excess water (step S
2) The water-containing pulp sheet in that state is put into a kneading machine and kneaded for a predetermined time (step S3). Continuing,
In order to improve workability, an appropriate amount of water is added to the kneaded product to give it some fluidity (step S4), and further, an interfiber bonding component is added and mixed (step S5). continue,
This mixture is put into a mold capable of dehydration molding and dehydrated under pressure (step S6). Further, it is heated and dried under this pressure (step S7). Subsequently, heating and pressurization are performed, and a predetermined temperature and a predetermined pressure are maintained for a predetermined time to advance plasticization (step S8). Then, it is slowly cooled (step S9) and demolded (step S10) to obtain a thin plate-like wood-based substrate.

FIG. 3 is a conceptual diagram showing a main part of the kneader 10 used for manufacturing the wood-based base material 1 according to the present invention. The kneader 10 includes two blades 12 and 1 each having a substantially triangular cross-section in a fixed mixing tank 11 and rotating in opposite directions.
2, the hydrous pulp sheet 14 is charged into the interior of the fixed mixing tank 11 through the opening gap 13 formed at the center of the upper surface of the fixed admixture tank 11, so that the hydrous pulp sheet 14 is formed by the blades 12, 12 having a substantially triangular cross-section. , Kneading and fibrillation. The kneading time is important here,
The influence on the bending performance will be described later.

The shapes of the blades 12, 12 of the kneader 10 are not limited to those shown in the figure, but may be appropriately selected in consideration of the kneading time and the fibrillation relationship. In addition to the kneader, it is also possible to defibrate using another mixing machine such as a ball mill. In any case, test the relationship between kneading time and fibrillation and select an appropriate one.

Further, the progress of fibrillation of kraft pulp fibers changes with the passage of kneading time,
As a qualitative evaluation method for evaluating the progress, the surface of the dried preform after drying is apparently different in appearance, and therefore a method of measuring the color of the state is effective.

FIG. 4 is a schematic view showing a die (FIG. 4a) and a press (FIG. 4b) used for producing the wood-based material 1 according to the present invention. Here, a cylindrical mold 20 is used to form a circular shaped thin plate. The kneaded material or the one in which the interfiber bonding component is mixed is placed in the mat state 1a and sandwiched between the upper and lower inner frames 21 and 22 of the mold 20, and is pressed by the hot press machine 25 as shown in FIG. 4b.

According to the manufacturing flow shown in FIG. 2, the kneader 10 shown in FIG. 3, the mold 20 and the press 2 shown in FIG.
5 was used to manufacture a molded thin plate under the following manufacturing conditions, the bending Young's modulus was 13 GPa and the bending strength was 150.
A thin plate-shaped substrate 1 (density 1.4 g / cm ² ) having a pressure of MPa was obtained.

[0027] ・ Pulp sheet-Craft pulp made from North American softwood ・ Boiling water immersion 1 minute -Drying and drying-pulp sheet water content 2% ・ Mixing time by kneader 20 minutes                 (Kneading speed: 50 rpm, kneading temperature 0 ° C to 80 ° C) ・ Hot press temperature rise → 150 ° C (press pressure: 100MPa)                   Compressed at 150 ℃ for 30 minutes

Next, a test piece (length 40
mm × width 8 mm × thickness 1.5 mm) and the bending performance evaluated by a three-point bending test (JIS-K7203) is shown in FIGS. 5a and 5b. FIG. 5a is a graph showing the effect of kneading time on flexural modulus.
b is a graph showing the influence of the kneading time on the bending strength.

As shown in the figure, when no kneading was performed by the kneader (kneading time: 0), the flexural modulus was 3 GPa.
A molded product having a bending strength of ˜3.5 GPa and a bending strength of 40 MPa to 50 MPa was obtained. In addition, the bending performance was improved as the kneading time was increased up to the kneading time of 20 minutes. And
If the kneading time exceeds 20 minutes, the flexural modulus of the molded product will be 1
It reached 0 GPa and also the bending strength reached 120 MPa. This value is about 3 times the value when the kneader was not used. Further, when the kneading time exceeded 20 minutes, the color of the molded product also changed from white to light green, and the appearance of a light-transmitting plastic appeared.

Table 1 shows the kneading time (minutes) and bending strength (MO
R), flexural modulus (MOE), and density measurement data. Both increase with the increase of kneading time,
It can be seen that the kneading time exceeds 10 minutes and the plateau has been leveled. The density is almost the same.

[0031]

[Table 1]

From the above results, it can be understood that the degree of kneading the pulp fibers by the kneader plays an important role in improving the adhesion between the fibers.

FIG. 6 is a graph showing the influence of whether or not a kneader is used and the additive (interfiber binding component) on the bending strength. The vertical axis shows the bending strength (unit: MPa), and the horizontal axis shows the combination of the types of additives. Despite not using a kneader, the combination composition of kraft pulp fiber (KP) and starch paste exhibits a bending strength (MOR) of 150 MPa or more. As for the amount of starch paste added, a bending strength of 20% was obtained rather than 10%. Measurement data is KP + starch paste 1
At 0%, 149.4 MPa, KP + starch paste 20
% Was 167.5 MPa.

On the other hand, when the kneader was used, the flexural strength of the thermomechanical pulp (TMP) was low (measurement data was 73.3 MPa), as expected, because lignin remained. As expected, kraft pulp (KP) had a very small amount of residual lignin, and thus exhibited high bending strength alone (measurement data: 130.4 MPa). Furthermore, I also tested the combination of kraft pulp and wood flour,
The effect of improving the bending strength due to the addition of wood powder was not observed. As measurement data, 134.7 MPa when KP + 10% wood flour, 134.5 MPa when KP + 10% wood flour.
It was 5 MPa.

FIG. 7 is a micrograph showing the effect of kneading with a kneader. Before the kneading, the pulp fibers retain their rigidity, but the kneading makes the pulp fibers soft, Furthermore, branching and entanglement, and generation of fine fibers are also seen. This can be confirmed more clearly by the enlarged photograph. From the above results, lacquer addition of starch paste as an interfiber binding component has a great influence on the improvement of bending performance, and the influence of pulp fibers, especially kraft pulp fibers, on the bending performance, rather than wood flour, is great. It will be understood that

In addition to starch paste, glucomannan, which is a konjac ingredient, can be used as a binder for binding fibers. Besides, gelatin, casein,
Dextrin, gum arabic, sodium alginate, polyvinyl alcohol, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose and the like can also be used as the biodegradable binder component,
In each case, the relationship between the kneading time and the bending performance is determined, and the materials are used under optimum conditions.

Further, by removing the condition of having biodegradability, a phenol resin can be used as a binder to improve water resistance, and the production method according to the present invention can be used for ordinary wood modification. The drug can be used without any restrictions. Further, by introducing a foaming agent, it is possible to further lower the density (about 0.7 to 0.8) without significantly deteriorating the bending strength performance.

[0038]

Industrial Applicability According to the present invention, it is possible to provide a wood-based base material obtained by reconstructing a plant fiber material having high strength by a method with a low environmental load, and a method for producing the same. Since such a wood-based base material can be recycled like paper and has biodegradability, it becomes an environment-friendly base material.

Furthermore, by molding a composite of different materials, it is possible to easily use and separate the wood-based base material after separating it from the different materials so that it can be used for electronic devices such as computers, mobile phones and various home appliances. It can also be used as a collectable resource for frames, printed circuit boards, instant cameras, etc.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the chemical structure of a wood-based substrate according to the present invention.

FIG. 2 is a manufacturing flow sheet showing a manufacturing process of a wood-based substrate according to the present invention.

FIG. 3 is a view showing a main part of a kneader used for manufacturing a wood-based material according to the present invention.

FIG. 4 is a view showing a die and a press used for producing a wood-based material according to the present invention.

FIG. 5a is a graph showing the effect of kneading time on flexural strength, and FIG. 5b is a graph showing the effect of kneading time on flexural modulus.

FIG. 6 is a graph showing influences of whether or not a kneader is used and additives (interfiber binding components) on bending strength.

FIG. 7 is a micrograph for confirming the effect of kneading using a kneader.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wood type base material, 2 ... Interfiber bond point, 3 ... Single fiber pulp, 4 ... Interfiber bond component, 10 ... Kneader, 12 ... Blade, 14 ... Water-containing pulp sheet, 20 ... Mold, 25 ... Press machine

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B27N 1/00-9/00 D21J 1/04

Claims (7)

(57) [Claims] 1. Fibrillation of pulp fibers by kneading
As a result of the progress of
It becomes plasticized by being placed under compression
It is a sheet-like wood-based substrate made of pulp fiber aggregates.
Between the adjacent fibrils at the interfiber bonding points
A wood-based base material having a strong bond formed therein . 2. An interfiber bonding component is present at the interfiber bonding point.
Each pulp fiber is intercalated by the interfiber bonding component.
Characterized by being firmly bonded to
The wood-based base material according to claim 1 . 3. The wood-based substrate according to claim 1, wherein the pulp fiber is kraft pulp fiber. 4. The wood-based base material according to claim 2, wherein the interfiber bonding component is a natural adhesive. 5. A warm water impregnation dehydration step of impregnating a sufficient amount of warm water into a pulp sheet-shaped body made of pulp fibers, and then dehydrating and removing excess water, and the pulp sheet-shaped body impregnated with warm water, A kneading step of kneading for a predetermined time with a kneader to obtain a kneaded material, a fluidity adjusting step of adding and mixing a predetermined amount of water to the kneaded material to adjust fluidity, and obtaining a molding preparation, and the molding preparation. In a molding die, the dehydration step of dehydrating to a first water content by pressurizing the molding preparation accommodated in the molding die, and the molding adjusted to the first water content. A drying step of drying the preparation under pressure to obtain a preformed dried material adjusted to a second water content; and the preformed dried material under a heating range of 120 ° C to 200 ° C and 5 MPa to. Predetermined plasticizing conditions under a pressure range of 100 MPa In the above, a heating and pressurizing holding step of holding for a predetermined time, and a wood-based base material comprising a pulp fiber aggregate that has been plasticized and fibrillated is produced to produce a wood-based base material. Production method. 6. The method for producing a wood-based substrate according to claim 5, wherein in the fluidity adjusting step, an interfiber bonding component is further added. . 7. The method for producing a wood-based substrate according to claim 5, wherein a kneader is used as a kneader in the kneading step.