JP3486637B2 - Binder-free wood material production method from waste paper - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a wood material, which is made of waste paper and does not require a binder.

[0002]

The main constituents of natural wood consist of cellulose, also called fibrin, and lignin and hemicellulose, which function as reinforcing and binder materials. Cellulose is a polymer formed by condensing glucose units into long chains, and is sometimes called fibrin.
Hemicellulose is also a polymer in which several kinds of sugars are linked in a chain, but the chain is not as long as that of cellulose. In addition, lignin is a complex organic polymer that is produced inside a plant so that cells become woody, lose their softness, and become hard.

The above cellulose and lignin are the most abundant natural polymers on the earth, and in particular,
Natural wood has been used as a building material, daily necessities material, etc. since ancient times, but the demand for paper as a raw material has increased too much in recent years, and the impact of unplanned deforestation on the global environment has been ignored. It is a place that cannot be done.

[0004] Further, although paper produced from natural wood as a raw material is used once, about 50% is recycled and reused as a raw material for paper, but the recycling rate can be further extended to 65%. Has been done. In order to recycle used paper, it is necessary to use a large amount of water resources and a large-scale wastewater treatment facility as the used paper is dissolved in a large amount of water using a stirring dissolver called a pulper and the pulp is separated by specific gravity. So a specific large-scale specialized mill (mainly a paper mill far from the city)
Since it can only be handled, transportation costs are high, and the processing plant is often a paper manufacturing company, it tends to be specified as a recycled paper raw material.

Further, the mechanical pulp waste paper used for newsprint and magazine paper is inexpensive for new newsprint and magazines themselves, and therefore has little economic advantage to be used as a recycled material for paper. It is said that it is not economically feasible to collect used paper at high cost, and the recycling rate is declining even more in Japan.

Therefore, various attempts have been made in the past to utilize used paper as a raw material for materials with high added value other than recycled paper, and as a representative proposal, research has been conducted for a long time to return used paper to the original wood material. .

The conventionally proposed method for producing a wood material using waste paper as a raw material is that a waste paper (divided into small pieces) is filled with 10 to several tens of percent of a synthetic resin (usually a thermosetting synthetic resin). It is mixed as a binder and pressed and heated.

[0008] That is, in natural wood, lignin is mainly present in cells (some of which are also between cell walls and also function as a binder). Since high temperature heating and high pressure are applied, the lignin existing in the cells is also pushed out of the cellulose fiber, and covers most of the outer surface of the cellulose fiber.

Since this lignin is a chemically very stable substance, it is extremely difficult to restore the original binder function to lignin that has been once divided.
It has been said that it is necessary to newly add a binder that binds the cellulose fibers together.

[0010]

However, the conventional method of mixing the used paper with the synthetic resin as a binder has an economical problem. That is, although used paper can be obtained at low cost, since a large amount of expensive synthetic resin is added, the manufactured wood material has a problem that it is more expensive than natural wood.

The above-mentioned conventional method also has a problem that biodegradability is lowered. That is, unlike natural polymers such as cellulose and lignin, synthetic resins have the property of being less likely to be decomposed by microorganisms, and when the mixing ratio of synthetic resins exceeds 10% by weight, biodegradability is extremely reduced. do it,
There is a problem that even if it is landfilled as final disposal, it will not be decomposed naturally for many years. It should be noted that, if the mixing ratio of the synthetic resin is high as described above, there is a problem that the calorific value is large even at the time of incineration, which causes an abnormal high temperature of the incinerator.

Therefore, the present invention has been made in view of the above problems, and has a property closer to that of natural wood, with the mixing ratio of the synthetic resin as a binder being extremely reduced or not mixed as compared with the conventional method. It is an object of the present invention to provide a method for producing a wood material that does not require a binder and is made of waste paper from which wood material is obtained.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the constitution of the present invention, which has the above-mentioned claims as its gist, meets the above-mentioned object. And fluffy waste fiber, as the second step,
The waste paper fiber is brought into contact with ozone to perform ozone treatment to open the aromatic ring of the contained lignin and introduce a carboxyl group, and as a third step, the ozone-treated waste paper fiber is mixed with 10 to 30% by weight of water. Then, as the fourth step, technical means for pressurizing and heating the hydrated waste paper fiber is taken.

Further, in the invention of "claim 2", as the first step, a waste paper having a lignin content of 20 to 30% by weight is equilibrated with a water content of about 8 to 10% after leaving the waste paper in a natural state. In the state of water content or in the state of being dried to be equal to or less than the equilibrium water content, dry defibration is carried out to form fluffy waste paper fibers. In the second step, the waste paper fibers are contacted with ozone having a gas phase concentration of 2500 ppm or more The ozone treatment of opening the aromatic ring of the contained lignin and introducing the carboxyl group is performed, and as the third step, the ozone-treated waste paper fiber is subjected to water addition with a water content of 10 to 30% by weight, As a process, the technical means of taking sufficient heat to evaporate the water content while pressurizing the hydrated waste paper fiber is taken.

Further, in the invention of "Claim 3", as a first step, a waste paper having a lignin content of 20 to 30% by weight is equilibrated with a water content of about 8 to 10% after leaving the waste paper in a natural state. In the state of water content or in the state of being dried to be equal to or less than the equilibrium water content, dry defibration is carried out to form fluffy waste paper fibers. In the second step, the waste paper fibers are contacted with ozone having a gas phase concentration of 2500 ppm or more. The ozone treatment of opening the aromatic ring of the contained lignin and introducing the carboxyl group is carried out, and as a third step, the ozone-treated waste paper fiber is subjected to water addition with a water content of 10 to 30% by weight, As a process, the hydrated waste paper fiber is pressed and pre-molded, and the weight ratio of 5 is applied to the surface.
%, Water is evenly sprayed, and as a fifth step, technical means is provided for performing heating sufficient to evaporate the water content while pressurizing the waste fiber that has been temporarily molded.

[0016]

Next, the operation of the present invention will be described. In the present invention, by bringing dry defibrated waste paper fibers into contact with ozone, the aromatic ring of lignin is opened and a carboxyl group is introduced, and therefore, it exerts an action of imparting hydrophilicity to lignin. As described above, lignin is a chemically very stable substance, but the strong oxidizing power of ozone has a function of decomposing lignin.
However, even if it says that lignin is decomposed, it requires reaction conditions for decomposing lignin until it becomes a substance with a small molecular weight, but at the beginning of the reaction, the aromatic ring of lignin is first opened. The reaction of a certain degree may simply be brought into contact with ozone at room temperature. The reaction in which the aromatic ring of lignin is opened by ozone is prioritized over the reaction in which ozone decomposes cellulose. However, in the case of liquid-phase ozone, reactive oxygen species such as hydroxyl radicals are generated by the reaction between ozone and water, and both cellulose and lignin tend to be decomposed, so that cellulose fibers are damaged in the present invention. Do not use vapor phase ozone.
A reaction example of opening the aromatic ring of lignin and introducing a carboxyl group is as shown in "Chemical formula 1".

[0017]

[Chemical 1]

In the present invention, since water is added to the defibrated fibers of waste paper having improved hydrophilicity as described above, water is evenly attached to the surface of the defibrated fibers of used paper. Then, when the defibrated fibers of waste paper are heated and pressed in this state, condensation and formation of hydrogen bonds are performed in the presence of water vapor in which water is evaporated.

In the condensation reaction, as shown in 1, "Chemical Formula 2," the carboxyl groups formed in lignin by ozone form acid anhydrides.

[0020]

[Chemical 2]

2. The carboxyl group of lignin and the hydroxyl group of cellulose form an ester bond as shown in "Chemical Formula 3".

[0022]

[Chemical formula 3]

There are reaction forms "Chemical Formula 2" and "Chemical Formula 3", and since these reactions are carried out simultaneously, a binding reaction between cellulose and lignin and a coupling reaction between lignins are exhibited.

In addition, the formation of the above hydrogen bond is 1. Cellulose is mutually. 2. Cellulose and lignin. Occurs between and. This hydrogen bond has a bond strength that is inferior to that of a normal covalent bond by an order of magnitude or more, but when a complexly entangled fiber is hydrogen-bonded due to the presence of hemicellulose, the bonding force is boosted when grasped as the bonding force between fibers. To present. In addition, the hydrogen-bonding ability of lignin exhibits an action of being greatly improved by making lignin hydrophilic by ozone oxidation.

[0025]

EXAMPLES Next, examples of the present invention will be described in detail. First, according to the present invention, waste paper is dry defibrated to form fluff-like waste paper fibers.

The reason for adopting dry defibration in the present invention is that since dry defibration does not require a large amount of water resources, it can be processed in the city where waste paper is mainly generated, and it is a conventional large-scale specialized factory in the suburbs. It is economical because there is no transportation cost to transport to.
Further, wet defibration requires a large amount of energy for drying later, and dry defibration requires less energy for drying, which is also a major reason for adopting dry defibration.

As a specific method of the dry defibration, waste paper may be pre-cut and defibrated by a conventionally known crushing device, but since pulp fibers are used in the present invention, it is crushed into powder. Instead, it is desirable to defibrate in a fluffy manner, and therefore it is desirable to apply a relatively small force to the defibration frequently and for a long time. Therefore, by adopting a method in which waste paper that has been precut is placed in the air flow and continuously collides with the fixed wall, defibration with a long fiber length can be performed, and a high-speed rotating blade is housed in an internal gear-like casing, After passing the waste paper conveyed by the air flow, the waste paper is defibrated in sequence while colliding with the uneven surface in the casing by the high-speed rotating air flow generated by the high-speed rotating blades, and fluff-like waste paper defibration fiber is obtained. there were.

The waste paper used in the present invention is a mechanical pulp waste paper having a lignin content of 20 to 30% by weight, and a state of equilibrium water content of about 8 to 10% when the waste paper is left in a natural state. Or, use a product in a state of being dried to an equilibrium water content or less. Chemical pulp has mostly removed lignin contained in natural wood in the pulp manufacturing process, but mechanical pulp contains lignin, which is the basis of the properties of wood, as it is (usually, the lignin content is around 25% by weight). Therefore, the present invention uses mechanical pulp waste paper to effectively utilize lignin. It should be noted that some chemical pulp waste paper may be mixed in.

For dry defibration of waste paper, it is desirable that the raw waste paper is in a dry state as much as possible in order to obtain a long and uniform dry defibration. However, when the waste paper is left in a natural state, the water content is 8 to 10. %, It is possible to dry defibrate sufficiently, but the wet waste paper has a tendency to be unable to be defibrated efficiently by dry defibration because it exhibits tackiness, fiber fragility and the like. Therefore, it is desirable that the used paper that has been wetted be dried positively or be stored in a humidity-controlled warehouse for a certain period of time to be dried at a water content below the equilibrium moisture content before being dry defibrated.

Next, in the present invention, ozone is brought into contact with the waste paper fibers to carry out ozone treatment for opening the aromatic ring of the contained lignin.

The ozone used in the ozone treatment is gas phase ozone obtained by ozoneizing air or oxygen as a raw material and oxygenating the oxygen in the raw material gas with an ozonizer (mainly a discharge type ozonizer). is doing.

The gas-phase ozone is used for selectively ozone-treating lignin without destroying cellulose as described above. In the selective ozone treatment for opening the aromatic nucleus of lignin, contact with high-concentration ozone for a short time is effective, and 2500 ppm or more, preferably 5000 p.
It was effective to use ozone above pm .

Since the contact between waste paper fibers and ozone is gas-solid contact, if ozone is injected into a simple mixing device, for example, a static mixer provided in the middle of the air transport path of waste paper fibers, ozone can be easily contacted uniformly. It is possible. Since ozone may also oxidize the air transportation device itself, it is necessary to configure the ozone treatment device section with an ozone resistant material.
Of course, it is also necessary to prevent unreacted ozone from being released into the atmosphere.

Next, in the present invention, the ozone-treated waste paper fiber is subjected to water addition in a weight ratio of 10 to 30%. This water is heated later to improve the reactivity between cellulose and lignin and to obtain hydrogen bonds between them, and the results of the experiment show the effect at a mixing ratio of about 10% by weight.
The greater the mixing ratio, the greater the effect. However, if the weight ratio exceeds 30%, the moisture remaining in the waste paper swells during the next pressurization and heating, causing a rupture phenomenon and a uniform wood quality. This is because the material cannot be obtained.

The water addition is carried out after dry defibration of waste paper and ozone treatment. When water is added before dry defibration, the defibration efficiency is lowered as described above, and when water is added before ozone treatment, water addition is the same as described above. The selective ring-opening property of lignin, such as contact with liquid-phase ozone, is impaired.

Further, since the above-mentioned rupture phenomenon is unlikely to occur in the portion close to the surface of the waste paper fiber which is pressurized and heated in the next step,
The water content may be 30% or more by weight, and “claim 3”.
In the invention described above, the hydrated waste paper fiber having a water content of 10 to 30% by weight is pressed and temporarily molded, and water having a weight ratio of 5% or less is uniformly sprayed on the surface thereof. By doing so, a layer having a high water content is formed from the surface to a certain depth (the stronger the compression of temporary molding, the more the spray water stays on the surface side). Then, when this was pressurized and heated in the next step, the surface thereof tended to be hard and smooth.

It should be noted that the water sprayed on this surface has the effect of improving the releasability from the manufacturing die for pressurizing and heating, and when the manufacturing die is mirror-finished is used. There was no adhesion phenomenon to the manufacturing mold.

The amount of water to be sprayed is set to 5% by weight or less in the above description. When water of 5% by weight or more is sprayed, the water retaining capacity of the very surface of the waste paper fiber is exceeded and the water is deep. Because it invades.

In the present invention, the hydrated waste paper fibers are pressurized and heated sufficiently to evaporate the water content.

Since the above-mentioned pressurization is very bulky for the waste paper fiber, it is convenient to carry out the pre-treatment as a pretreatment for the subsequent handling. When a plate-like wood material is obtained, it has a predetermined thickness with a conventionally known forming machine. The mat-like shape may be temporarily formed, and this may be heated under pressure with a heating press. If you want to obtain a non-planar molded body, granulate waste paper fibers and press
It suffices to put it in a heating mold.

The above-mentioned pressurization / heating conditions are 110 ° C. or higher,
Desirably heating at around 130 ° C and 15 Kgf / cm ²
The above pressurization is desirable. In this embodiment, about 300
(mechanical pulp) waste paper fiber mat with a specific gravity of 0.
When 04) was pressed at 130 ° C. and 15 Kgf / cm ² for 10 minutes, a strong wood board having a specific gravity of 0.9 and a thickness of 12 m was obtained. This wooden board has a bending strength of about 350 Kgf / cm ² ·
It has a Young's modulus strength of 38.000 Kgf / cm ² and has strength characteristics comparable to those of natural wood.

[0042]

As described above, the present invention is able to provide a method for producing a wood material that does not use a binder made of waste paper and that does not use a binder made of synthetic resin and that is made of waste paper. The fact that the binder is unnecessary means that the components of the obtained wood material are similar to those of natural wood, and the wood material obtained by the method of the present invention has a great feature that it can be further defibrated and reused after use. .

Further, since the present invention does not use a binder of synthetic resin, even if it is landfilled underground, it is naturally decomposed by microorganisms in the soil, and even if it is incinerated, it has the same calorific value as ordinary wood. It has the feature that it does not generate corrosive gas, and can provide excellent materials from an ecological perspective.

Further, in the present invention, an expensive synthetic resin binder is not used, and inexpensive (mechanical pulp) waste paper is used as a main raw material, and the waste paper is defibrated by a dry method in which no waste water is discharged. Therefore, it is possible to provide a method for producing a wood material that does not require a binder and is made of waste paper, which is expected to be widely used as an inexpensive recycled wood material that replaces natural wood because of its economical equipment cost and raw material cost.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoichi Tomimura, No. 1 Matsunosato, Kukizaki-cho, Inashiki-gun, Ibaraki Prefecture In the Forestry Research Institute of the Ministry of Agriculture, Forestry and Fisheries (72) Kazuo Kurihara 2570-4 Shimatsuzuru, Yamato-shi, Kanagawa Nishimatsu Construction Co., Ltd. Company Technology Research Institute (72) Inventor Wataru Takada 2570-4 Shimotsuruma, Yamato City, Kanagawa Nishimatsu Construction Co., Ltd. Technical Research Institute (72) Inventor Hirokazu Shioda 5-21-101 Minami-Aoyama, Minato-ku, Tokyo BMC Co., Ltd. (72) Inventor Toshinori Matsuda 5-5-21-101 Minamiaoyama, Minato-ku, Tokyo BMC Co., Ltd. (56) Reference JP-A-6-65881 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B27N 3/04 B27K 5/00

Claims (3)

(57) [Claims] 1. As a first step, dry defibration of mechanical pulp waste paper to form fluffy waste paper fibers, and as a second step, ozone is contacted with the waste paper fibers,
Ozone treatment to open the aromatic ring of the contained lignin and introduce a carboxyl group is carried out, and as a third step, the weight ratio of ozone treated waste paper fiber to 1
The fourth step is a method for producing a wood material that does not require a binder and uses waste paper as a raw material. 2. As a first step, a waste paper having a lignin content of 20 to 30% by weight is used in a state of equilibrium water content of about 8 to 10% by leaving the waste paper in a natural state, or an equilibrium water content. Dry defibration in the dried state to give fluffy waste paper fibers, and in the second step, 2500 ppm of gas phase in the waste paper fibers
Ozone treatment is performed by contacting ozone with the above concentrations to open the aromatic ring of the lignin contained and introduce carboxyl groups , and as the third step, the waste paper fiber treated with ozone has a water content of 10 to 30% by weight. The fourth step is a method for producing a wood material that does not require a binder and uses waste paper as a raw material. The fourth step is to heat the hydrated waste paper fiber while heating the fibers to evaporate the water content. 3. In the first step, a waste paper having a lignin content of 20 to 30% by weight is used in a state of equilibrium water content of about 8 to 10% by leaving the waste paper in a natural state, or an equilibrium water content. Dry defibration in the dried state to give fluffy waste paper fibers, and in the second step, 2500 ppm of gas phase in the waste paper fibers
Ozone treatment is performed by contacting ozone with the above concentrations to open the aromatic ring of the lignin contained and introduce carboxyl groups, and as the third step, the waste paper fiber treated with ozone has a water content of 10 to 30% by weight. The hydrated waste paper fiber is subjected to the fourth step, and the hydrated waste paper fiber is pressed and temporarily molded, and water having a weight ratio of 5% or less is uniformly sprayed on the surface, and the fifth step is the temporarily molded waste paper fiber. A method for producing a wood material that does not require a binder and is made of waste paper and is heated while pressurizing the water to evaporate the water content.