JPS5839062B2 - Method for producing a lightweight plate-like body made of rice husk as the main material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an inexpensive lightweight plate-like body mainly made of rice husk, which has extremely high practical value.

In the past, many studies have been conducted on methods for producing inexpensive, lightweight plates made mainly from rice husks, which are a by-product of rice hulling. This method is based on a dry method or semi-dry method in which rice husks are hardened with an adhesive, and there are almost no reports of methods using a papermaking method.

The reason why the paper-making method, which has long been used as a continuous manufacturing method for fiberboard such as insulation boards and hardboards, is rarely adopted as a method for manufacturing lightweight plate-like bodies whose main material is rice husk is that This is because when producing lightweight plate-like bodies by the papermaking method using slurry as the main material, the following problems arise, and as a result, the characteristics of the papermaking method are lost. .

First, while rice husk has excellent compression recovery properties, its outer surface is made of silica, so it has extremely poor adhesion to adhesives, a unique property not found in other materials. As a result, the hydrous mat obtained from the rice husk-based slurry is simply a combination of oval rice husks overlapped in a point-bonded state, even if it contains a relatively large amount of adhesive. Moreover, since the adhesive force at the point bonded portion is weak, its shape retention is extremely poor and the shape is easily lost.

Therefore, when obtaining a lightweight plate-like body by a paper-forming method using a slurry whose main material is rice husk, in order to prevent the water-containing mat from losing its shape, the paper-forming speed of the slurry, the pressurized suction dehydration speed of the water-containing mat, and the water-containing mat's Since the conveyance speed, etc. of the paper must be significantly reduced, productivity, which is one of the most important features of the papermaking method, is completely lost.

In other words, the excellent compressive resilience of rice husks is a great advantage from the point of view of reducing the weight of a plate-like material or imparting appropriate compression-resilient properties to a lightweight plate-like material; From the perspective of mold retention, this is a fatal disadvantage.

On the other hand, there are many major problems in the physical properties of a lightweight plate-like body obtained by subjecting a hydrous mat to heat-pressure molding and drying and simply bonding rice husks with an adhesive.

In other words, rice husk originally has extremely poor adhesion to general-purpose adhesives, so the bonding force between rice husks is very weak, and even if a large amount of adhesive is mixed in to compensate for this lack of bonding force, Not only is it not possible to obtain a substantial binding force between rice husks in relation to the amount of mixture, but the resulting product loses the greatest advantage of rice husks, which is that it is an inexpensive material, and becomes extremely expensive. The properties of the material, such as lightness, compression recovery, breathability, heat retention, heat insulation, sound absorption, etc., are significantly impaired.

Furthermore, the lightweight plate-like material obtained by forcibly bonding rice husks by mixing a large amount of adhesive also has the fundamental problem of poor adhesion between the rice husks and the adhesive. A fatal practical drawback is that the bonding force between rice husks deteriorates over time, such as the bonding force at the interface between the rice husks and the adhesive gradually decreasing due to expansion and contraction of the rice husks due to environmental changes.

When using an adhesive made of shattered liquid Shioib, the adhesive tends to migrate to the surface area during heating and pressure molding of the hydrous mat or when it dries, and there is very little adhesive inside the lightweight plate. Since only a small amount of adhesive remains, the adhesive has no substantial effect, and therefore the bonding force between the rice husks inside the lightweight plate is extremely small.
A fatal problem arises in that the rice husks fall off when touched with a finger.

In addition, by mixing a large amount of adhesive into the slurry,
The method of improving the shape retention of a water-containing mat or the physical properties of a lightweight plate is based on the pot life or freeness of the slurry,
Furthermore, it has a negative effect on the dehydration properties of the water-containing mat under pressure, and there are also problems in adjusting the adhesive concentration in the white water and the stability of the white water when using the reduced white water in the papermaking process.

In addition, rice husks have poor compatibility with water and tend to trap air during mixing and stirring, so a large amount of rice husks floats to the surface of the water in the slurry, resulting in uneven distribution of rice husks in the slurry. Since it becomes difficult to continuously produce a water-containing mat with a constant thickness and quality, the major feature of the papermaking method, which is the ability to continuously produce plate-shaped bodies with a uniform thickness and physical properties, is lost. be exposed.

As many of the problems mentioned above remain unresolved,
Hitherto, there has been almost no attempt to manufacture a lightweight plate-like body using rice husk as the main material using a papermaking method.

On the other hand, in the conventional method of manufacturing rice husk plates, that is, the dry method or semi-dry method, a liquid main, powder, or granular type adhesive is used as a binder for the rice husk, and a mixture of rice husk and adhesive is formed into a mat. A lightweight plate-like body is produced by forming the rice husk and adhesive, followed by heat-pressure molding and drying. However, the major problems with these known production methods are the uniform mixing of the rice husks and the adhesive, and especially the difficulty in mixing the rice husks and the adhesive. There is a fundamental problem that it is difficult to uniformly form rice husk, and therefore, the resulting rice husk plate-like bodies are unsatisfactory, with partially uneven density and variations in bending strength and compressive resilience. .

Furthermore, the shape retention of the forming mat is also very poor, similar to that of the water-containing mat used in the papermaking method described above.

In addition, the manufactured rice husk plate-like bodies are made by bonding rice husk, which originally has extremely poor adhesive properties, to a strong II cup using a large amount of adhesive, and these have a temporary strength development. However, it is not favorable as it is accompanied by changes over time.

In addition, attempts have been made to incorporate fibers to improve the physical property problems, but when mixing rice husks, adhesives, and fibers, most of the fibers become intertwined with each other and partially form small lumps. Not only is the effect of incorporating fibers on the improvement of physical properties hardly recognized, but also a large amount of fibers adheres to the mixing device and forming device, making uniform mixing and forming even more difficult.

In addition, in a method of manufacturing a plate-shaped body by a dry method or semi-dry method using rice husks, adhesives, and fibers,
A method has also been reported in which a sludge-like bulb in which an adhesive and a bulb are mixed in advance is used to uniformly mix the rice husks and improve the bonding force between the rice husks, but this method is also applicable to the paper-making method of the present invention. The dispersibility of the bulbs is significantly poorer than in the case of conventional methods, and therefore a much larger amount of adhesive is required to bond the poorly adhesive rice husks.

As a result, the resulting plate-like material does not have the characteristics of rice husk, such as lightness and compression resilience, as described above, and the bonding force between the rice husks deteriorates due to expansion and contraction of the rice husks due to environmental changes. However, there is a problem in that physical properties deteriorate over time.

As mentioned above, many problems are recognized when looking at the dry method or semi-dry method for producing rice husk plates.

As a result of long-term research into a practical and inexpensive method for manufacturing lightweight plate-like materials mainly made from rice husks, the present inventors have found that after fibrillation with water, dehydration, and drying, strong bonding strength between fibers and other properties are achieved. By using bulbs that are more flexible and more easily entangled than ordinary fibers, we have discovered a new manufacturing method that is not found in conventional methods that use large amounts of adhesive. .

Therefore, by using pulp, the present invention achieves excellent bonding strength and shape retention with very little deterioration over time between rice husks without using adhesives, and the main component of both rice husks and pulp is cellulose. Because of this, there is a synergistic effect in that the familiarity of the two differences is further improved.

That is, the present invention utilizes the binding force of pulp as a binder to bind rice husks together, and also solves the many problems encountered when producing light plate-like bodies mainly made of rice husks using conventional papermaking methods. This problem can be solved by utilizing the excellent properties of rice husks, making it possible to adopt the papermaking method.As a result, many problems seen in dry or semi-dry production methods can be solved, and the favorable properties of rice husks can be solved. An object of the present invention is to provide a method for producing an inexpensive lightweight plate-like body mainly made of rice husk, which has various properties and has excellent properties that can be put to practical use.

The present invention will be explained in detail below.

In the present invention, first, rice husks, pulp, and water are stirred and mixed to create a slurry.

At this time, as shown in FIG. 1, the pulp 3 becomes fibrillated and becomes entangled with the rice husk 1 (the surface of the rice husk, the fine thorns 2 etc. that are attached to the outer wall of the rice husk), so that the pulp 3 of each rice husk 1 is
At the same time, on the other hand, the pulps 3 become entangled with each other.

Therefore, since the rice husks 1 in the slurry are bound together by the pulp 3, they do not float on the water surface in the slurry and are uniformly dispersed throughout the slurry.

Next, this slurry is made into a water-containing mat using conventional paper making methods such as Fourdrinier method, circular wire method, and casting method.
Due to the effect of mixing pulp, it is possible to continuously form a water-containing mat with a constant thickness and quality1, and the water-containing mat also has excellent freeness and shape retention.

Therefore, the characteristics of the papermaking method, namely high productivity and product uniformity, can be fully utilized.

After that, the water-containing mat, whose water content has been adjusted to an appropriate level by performing pressure suction dehydration, etc., is heated and press-molded as appropriate, so that the water-containing mat is set to a predetermined thickness and has a smooth surface. The rice husk becomes wrapped in a state due to the excellent intertwining of the pulps, and the flexible adhesive action that only the pulp has is developed in the contact areas between the pulps and the contact areas between the rice husk and the pulp. It is strongly bonded by the soft bonding force unique to pulp.

In the manner described above, an inexpensive lightweight plate-like body whose main material is rice husk is manufactured.

In addition, when heat-pressing molding the water-containing mat, a continuous heat-pressing molding machine manufactured by Endless Bell) J.B., a hot press machine, or the like can be used.

However, the amount of pulp mixed in the present invention must be 10 to 100 parts by weight, preferably 20 to 90 parts by weight, per 100 parts by weight of rice husks.

If the amount of pulp mixed in is lower than the range specified in the present invention, the amount of K mixed with the rice husks is insufficient, and as a result, the rice husks float up in the slurry, and the water-containing mat is formed. Problems such as poor shape retention arise, and the obtained lightweight plate-like material becomes difficult to put into practical use due to poor physical properties.

On the other hand, if the amount of pulp mixed in is higher than the range specified in the present invention, pulp is significantly more expensive than rice husk, so the advantage of rice husk in terms of cost reduction cannot be utilized.
The physical properties of the lightweight plate-like material are similar to those of pulp board, and the lightness, compression resilience, breathability, heat retention, and
Since excellent properties such as heat insulation and sound absorption are no longer exhibited, the substantial value of using rice husks is lost.

The pulp used in the present invention may be mechanical pulp, semi-chemical pulp, bleached pulp, unbleached pulp, waste paper pulp, etc., and in consideration of economic efficiency, it is preferable to use recycled pulp such as waste paper pulp.

On the other hand, by adding a very small amount of auxiliary binder to the slurry, the synergistic effect between the binding strength of the pulp and the auxiliary binder is mutually enhanced, and as a result, the resulting lightweight plate-like material is accompanied by a significant increase in cost. This method is preferable because it provides even more excellent physical properties.

The effect of the auxiliary binder is usually fully exhibited if it is added to the slurry in such a way that the substantial solid content of the auxiliary binder is 0.5 to 7 parts by weight per 100 parts by weight of rice husks in the lightweight plates. The amount to be mixed must be determined depending on the type of auxiliary binder, taking into consideration the phosphor effect on the physical properties of the lightweight plate, the effect on slurry papermaking, and the pressurized suction dehydration of the water-containing mat.

Furthermore, since the white water generated during slurry papermaking and the like contains an extremely small amount of auxiliary binder, it can be used for reduction while replenishing the insufficient auxiliary binder.

The auxiliary binders used in the present invention include various resin emulsions such as urea resin, melamine resin, urea-melamine cocondensation resin, phenol resin, and vinyl acetate resin, various synthetic or natural water-soluble materials such as polyvinyl alcohol, carboxymethyl cellulose, and glue. adhesive powders and their aqueous solutions, thermoplastic resins such as polyethylene and aqueous polypropylene, holatometal adhesives, various starches that exhibit their adhesive strength by being gelatinized by heating, cement, gypsum water glass, etc. These are inorganic adhesives and the like, and these can be used alone or in combination of two or more.

In addition, the rice husks used in the present invention can be sufficiently used as by-products during hulling, and there is no need for any particular treatment.

Furthermore, rice husks may be crushed and used as appropriate.

In addition, inorganic and organic fibers, various lightweight aggregates, various extenders, twist retardants, fungicides, surfactants,
Antifoaming agents, waterproofing agents, fixing agents, curing agents, coloring agents, etc. may be mixed.

In addition, in the present invention, the order in which the water-containing mat obtained by the paper-making method is heated and pressure-molded and then dried is not taken, but the water content of the water-containing mat, the auxiliary binder or additives contained in the water-containing mat, etc. Depending on the type of
Before heating and press-molding the water-containing mat, it is preliminarily dried.
There may be a method in which the mat is then heated and press-molded, or if the moisture in the water-containing mat is sufficiently dispersed by heating and press-molding and drying is involved, there is no problem in omitting the subsequent drying.

Next, the effects of the present invention will be explained.

First, from a manufacturing perspective, the paper-making method, which has traditionally been used as a method for manufacturing lightweight plate-like bodies using rice husks as the main material, suffers from reduced productivity due to poor shape retention of the water-containing mat, and from the lifting of the rice husks in the slurry. This causes major problems such as non-uniformity of thickness and physical properties of the lightweight plate-like body, poor physical properties of the lightweight plate-like body, poor drainage performance due to the use of a large amount of adhesive, and difficulty in reducing use due to gelation of white water. Therefore, it was difficult to adopt the paper-making method because the excellent medullary length inherent to the paper-making method was not fully utilized. However, by incorporating pulp, these problems were solved and the paper-making method became possible, so by using ordinary paper-making equipment. A lightweight plate-like body with uniform thickness and physical properties can be manufactured continuously and efficiently.

As a result, it is possible to solve the problem that the thickness and physical properties of the lightweight plate-like body are non-uniform, which occurs in dry or semi-dry manufacturing methods.

In terms of the physical properties of the resulting lightweight plate-like material, the individual rice husks have a strong bonding force, and are firmly bonded by the pulp that is compatible with the rice husks, so expensive adhesives are almost unnecessary. There is no need to use rice husks, so the lightweight plate-like material is very inexpensive and at the same time has all the excellent properties of rice husk.

In addition, the problem of the extremely weak bonding force inside the plate-like body, which occurs in lightweight plate-like bodies obtained by bonding rice husks with adhesive, has been solved, and furthermore, the expansion and contraction of the rice husk due to environmental changes is unique to pulp. Since the soft bonding force of the rice husks allows sufficient absorption, the bonding force between the rice husks, in other words, the physical properties of the lightweight plate-like material are extremely stable over time.

Furthermore, by adding a very small amount of auxiliary binder, the synergistic effect between the binding strength of the pulp and the auxiliary binder is mutually enhanced, making it possible to obtain a lightweight plate-like material with even better physical properties.

As described above, the present invention has excellent effects, and the lightweight plate-like body obtained by the present invention also has many excellent physical properties, so it can be used as a material for ceiling materials, wall materials, and roof base materials. ,
It can be expected to have a wide range of uses, including insulation, heat retention, sound-absorbing materials, partitions, tatami floors, and composite materials with other common materials.

Next, the present invention will be explained based on examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 10 parts by weight of waste paper pulp and 2 parts by weight of water per 100 parts by weight of rice husk
000 parts by weight was added, and the slurry obtained by stirring and mixing them was placed in a mold with a metal net with a mesh size of 0.3 mm on the bottom, and the rice husk and waste paper pulp, excluding water, were mixed together. Pour so that the total weight is 42009/m”,
Then, it was dehydrated under appropriate pressure to obtain a water-containing mat with a thickness of about 25 m7IL.

Next, the water-containing mat was sandwiched between coal plates with a mesh size of 0.2 and placed in a hot press machine with the heating platen temperature adjusted to 170°C, and the heating platen gap was set to 20m7/L for 15 minutes. Molded under heat and pressure.

Example 2 In Example 1, 10 parts by weight of the waste paper pulp was added by drying the water-containing mat that still contained water after heating and pressure molding using a hot air dryer at a temperature of 150°C to create a lightweight plate-like body A. A lightweight plate-like body B was produced in the same manner as in Example 1 except that the amount was changed to 30 parts by weight.

Example 3 A water-containing mat obtained using the same blended slurry as in Example 2 was dried for 35 minutes using a hot air dryer at a temperature of 150°C, and then the water-containing mat was dried on a caulk board with a mesh size of 0.2 mm. A lightweight plate-like body C was produced by sandwiching the sheets between the plates and applying the hot press machine with the hot platen temperature adjusted to 170° C., and heating and pressing the plate with the hot platen gap set to 20 m7IL for 15 minutes.

Example 4 A lightweight plate-like body was produced in the same manner as in Example 1 except that 10 parts by weight of the waste paper pulp in Example 1 was changed to 80 parts by weight.

Example 5 Example 2 except that the urea-melamine co-condensation resin emulsion was added to the slurry so that the lightweight plate-like body had a substantial resin solid content of 3.5 parts by weight based on 100 parts by weight of rice husk. A lightweight plate-like body E was created in the same manner as in Example 2.

Example 6 The same method as in Example 2 except that in Example 2, the actual corn starch solid content was added to the slurry so that the lightweight plate contained 4.5 parts by weight based on 100 parts by weight of rice/husks. A lightweight plate-like body F was created.

Comparative Example 1 In Example 1, instead of 10 parts by weight of waste paper pulp, a urea-melamine cocondensation resin emulsion was used in an amount such that the actual resin solid content was 15 parts by weight in the lightweight plate-like body based on 100 parts by weight of rice husk. A lightweight plate-like body G was produced in the same manner as in Example 1 except for this.

Comparative Example 2 To 100 parts by weight of rice husks, 30 parts by weight of waste paper pulp and 3.5 parts by weight of urea-melamine co-condensed resin emulsion (as actual resin solid content) were added, and these were stirred and mixed without papermaking. The sticky mixture was placed in a mold with a coal board with a mesh size of 0.2 mm on the bottom, and the total weight of the actual rice husk and waste paper pulp was 4200 g/m.
It was formed into a forming mat.

Next, the forming mat has a mesh size of 0.2.
Sandwich the plate with 1/4 inch coal board and raise the temperature of the plate to 170°.
Use a hot press machine adjusted to C, and set the hot plate gap to 20t.
A lightweight plate-like body H was produced by heating and press-molding the molded product for 15 minutes by setting it in a ran mode.

Comparative Example 3 To 100 parts by weight of rice husks, 30 parts by weight of waste paper pulp and 25 parts by weight of urea-melamine co-condensed resin emulsion (as actual resin solid content) were added, and the following method was used in the same manner as in Comparative Example 2 without forming paper. A plate-like body ■ was created.

Table 1 shows the state of the manufacturing process of each lightweight plate-like body obtained in the above Examples and Comparative Examples.

Furthermore, the physical properties of each lightweight plate-like body, pulp dispersibility, material price, etc. are shown in Table 2.

Looking at Table 1, in Comparative Example 1, that is, when creating a lightweight plate by the papermaking method without mixing pulp, even if a large amount of adhesive is used, many rice husks will float up in the slurry. Therefore, the dispersion state of the rice husks is poor, and the shape retention of the water-containing mat is also poor.

Furthermore, there is also the problem of poor drainage of the slurry due to the use of a large amount of adhesive.

Therefore, a method for manufacturing light weight plates of rice husk using a papermaking method that does not use pulp cannot be put to practical use.

Note that the dry methods shown in Comparative Examples 2 and 3 also have the problem of poor shape retention of the forming mat even if pulp is mixed.

On the other hand, Examples 1 to 6 of the present invention are excellent in the dispersion state and freeness of rice husks, the shape retention of the water-containing mat, and the like.

Therefore, by adopting the papermaking method, the major features of the papermaking method, namely high productivity and product uniformity, can be fully exploited.

According to Table 2, Examples 1 to 6 (A to F) produced according to the present invention are different from Comparative Examples 1 and 3, that is, those produced by the papermaking method using a large amount of adhesive, G, It has a better bending strength than the one made by the dry method by mixing pulp and a large amount of adhesive, and on the other hand, it is cheaper than these in terms of material cost.

Furthermore, when comparing the bending strength of each lightweight plate-shaped body immediately after and one year after aging, it was found that the strength of the one according to the present invention hardly decreased over time, and the bonding strength between rice husks was extremely stable over time. On the other hand, the comparative example in which the rice and husks were bonded together with an adhesive showed a considerable decrease in strength over time.

From these facts, it is clear that the pulp of the present invention and the inclusion of a small amount of auxiliary binder have a very excellent effect on the strength of the lightweight plate-like body.

On the other hand, in Comparative Example 2H, the amount of pulp used and the Q
This was prepared by a dry method using the same amount of adhesive or auxiliary binder solid content as Example 5E prepared according to the present invention, but the bending strength was significantly inferior to that of Example 5E.

Furthermore, although Comparative Example 3I was produced using a dry method, its strength was extremely low despite the fact that pulp was used and a considerable amount of adhesive was mixed therein.

Therefore, when using the dry method, even if pulp is used, due to poor dispersibility and poor entanglement, the soft bonding strength due to the unique adhesive action of pulp that can be obtained with the paper-making method cannot be obtained, and the effect of mixing pulp is It is clear that it is hardly being used.

Moreover, Example 2B, Example 5E, and Example 6F have the same amount of pulp mixed in, but Example 5E and Example 6F
contains very small amounts of auxiliary binder.

Therefore, in Examples 5E and 6F, the synergistic effects of the pulp binding strength and the auxiliary binder are mutually enhanced, and Example 2
It shows a much higher bending strength than B.

In addition, the strength of Example 5E and Example 6F is the same as that of Example 4 in which the amount of pulp mixed was increased without using an auxiliary binder.
Although it is almost the same as D, the material price is cheaper in Example 5E and Example 6F.

From these considerations, it is recognized that the incorporation of very small amounts of auxiliary binder is a preferred method.

Incidentally, in Example 2B and Example 3C, the order of heat-pressing molding and drying of the water-containing mat was reversed, but no difference in physical properties was observed.

Furthermore, the product according to the present invention is also excellent in terms of binding strength of rice husks.

As described above, the present invention enables the continuous and efficient production of inexpensive, lightweight plate-like bodies made of rice husk as the main material, which have excellent physical properties and are of extremely high practical value.

[Brief explanation of drawings]

FIG. 1 is an enlarged front view showing the entanglement of rice husks and pulp and the mutual entanglement of pulps in the present invention. 1...Rice husk, 2...Thorns on the outer wall of the rice husk, 3...Pulp.

Claims (1)

[Scope of Claims] 1. Rice husks, characterized in that a slurry containing 10 to 100 parts by weight of pulp per 100 parts by weight of rice husks is made into a water-containing mat by a paper-making method, and then the water-containing mat is heated and pressure-molded and dried. A method for manufacturing a lightweight plate-like body using as the main material. 2. A method for producing a lightweight plate-like body mainly made of rice husk according to claim 1, wherein an auxiliary binder is added to the slurry.