JPH1177623A - Novel wooden material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent material capable of being formed into various shapes while dispensing with wood resources apprehended to be exhausted, low in cost, easy to produce, imparting a natural feel or impression to a person, excellent in moisture resistance, water resistance and processability, generating no environmental pollution, easy in final disposal and generating no NOx gas. SOLUTION: A wooden material is obtained by immersing a fiber structure composed of non-wood part vegetable fibers in an emulsion type phenol resin dispersed aq. soln. and drying the impregnated fiber structure before molding the same. The excessive resin dispersed aq. soln. contained in the immersed fiber structure is removed before drying. For example, polyvinyl alcohol is used in the resin dispersed aq. soln. as a modifier for modifying a phenol resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood material which can be used for various structures such as furniture, civil engineering, architecture, woodwork, automobile interior materials, musical instruments and the like.

[0002]

2. Description of the Related Art Conventionally, wooden boards or veneer plywoods have been used for furniture, buildings, or various structures. Since the raw materials of these wooden boards and veneer plywood are domestically expensive, they have visited overseas, especially in Southeast Asia. However, recently in these Southeast Asian countries, the deforestation of forests and the depletion of resources have been concerned, and the export of log materials has been banned, making it difficult to obtain these raw materials year by year. These countries are trying to prevent deforestation by planting trees, which means that planting and forest management costs are added to the cost of timber, and soaring veneer or wood boards is inevitable. It is believed that there is.

[0003] One of the biggest drawbacks of veneer is that it can only obtain a flat or nearly flat shape. For example, it has been extremely difficult to obtain a product having a right angle or an acute angle such as an angle material, a channel material or a beam material, and a product having a free shape such as an automobile dashboard.

On the other hand, a fiber reinforced resin composite material (FRP) in which carbon fiber, glass fiber, aromatic polyamide fiber or the like is combined with a resin has been proposed as being lightweight and having excellent mechanical properties. It was relatively easy to obtain a material having a shape such as an angle material and a channel material.

[0005] However, the fibers used in these FRPs are products of state-of-the-art or advanced technologies and are extremely expensive, so that it is considered that a long time is required before they become inexpensive and general materials. Attempts have been made to reduce the cost by combining these FRPs with porous resin plates or honeycomb structures, but at the present time they are still expensive and can be used as general materials instead of veneer plywood. There is no prediction that it will be developed immediately. In addition, these FRPs are industrial products, and their uniformity and odor of man-made products do not match the recent trend of nature and nature.

Further, such fibers are nonflammable and heat-resistant, and a definitive final disposal method of the fiber-reinforced resin composite material using these nonflammable and flame-retardant fibers has not yet been established. It is expected to become a major environmental problem in the future.

In order to solve such a drawback, Japanese Patent Application Laid-Open No. Hei 7-124915 proposes a molded board made of non-woody plant fibers. This is obtained by spraying and attaching an aqueous dispersion of a thermosetting resin to an organic fiber, followed by molding.

However, this molded board has a large deformation such as warpage and swelling during use, and is inferior in workability such as sawing property, nailing property and wood screw holding property, and cannot be actually used. Met.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, that is, it is possible to obtain various shapes while eliminating the need for depleting wood resources, and it is inexpensive. It is an object of the present invention to provide an excellent material which is easy to manufacture, gives a natural feeling or impression to a person in contact, has excellent moisture resistance, water resistance and workability, is pollution-free, easy to dispose of finally, and does not generate NOx gas. Aim.

[0010]

According to a first aspect of the present invention, there is provided a woody material in which a fibrous structure composed of non-xylem plant fibers is immersed in an aqueous solution of an emulsion-type phenolic resin. It is a woody material formed by drying, molding and drying.

On the other hand, in the method for producing a woody material of the present invention, in order to solve the above-mentioned problems, a fiber structure comprising non-woody plant fibers is immersed in an aqueous solution of an emulsion-type phenolic resin. , Drying, and molding.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a binder to be used, a urea resin, a melamine resin, a phenol resin, an unsaturated polyester and the like can be considered. In the present invention, it is necessary that the phenol resin is used. That is, by using a phenolic resin, gas such as NOx and a large amount of black smoke are not generated even during incineration, and the moisture resistance and water resistance required when used as a substitute material for veneer plywood, for example, are satisfied. , And can be manufactured at a lower cost. The absence of gases such as NOx and a large amount of black smoke not only means that the final disposal can be done without pollution, but also prevents poisoning in the event of a fire when used as building materials or furniture. There are advantages such as safe evacuation. In addition, vegetable fiber has high hygroscopicity and water absorbency, and it is easily deformed by this moisture and causes trouble. However, it can be prevented by using a phenol resin.

The phenolic resin to be used is required to be an emulsion type because it can provide a woody material having excellent mechanical properties and no deformation or warpage. The reason why the emulsion type phenolic resin is excellent is unknown, but is considered as follows. In other words, after impregnating non-xylem plant fibers with an emulsion type phenol resin dispersion aqueous solution composed of an emulsion type (water dispersion type) phenol resin, the resin component is brought into contact with the fibers in the process of evaporating moisture when drying. get together.

Therefore, for example, even when a web of vegetable fiber is superimposed, impregnated with an emulsion-type phenol resin and dried as it is, the handleability until the subsequent molding step is good without any loss of shape.

Further, even when heated in a molding step such as a hot press treatment, the resin component gathered at the contact points between the fibers does not flow and stays as it is. Because the network is strong and there is no uneven distribution of resin and fiber,
It is considered that no deformation or warpage occurs.

In order to improve the above mechanical properties, the emulsion type phenol resin is not only made to be strong as a whole because a high molecular weight phenol resin is used, but also the resin flow in the molding step is increased. It is considered that this also contributes to the improvement of the mechanical strength.

Furthermore, since the resin flow during molding is small, the network between the fibers is maintained during molding, and there is no partial low-strength portion caused by the movement of the fibers. Even a wooden material using a woven fabric has extremely good appearance and mechanical properties without generation of openings or uneven density.

Further, when a fiber structure made of non-xylem plant fiber is immersed in an aqueous solution of an emulsion type phenol resin, the resin component adheres so as to cover the entire fiber surface, or the fiber surface is dried in a subsequent drying step. It is thought to cover the whole. As a result, the exposed portion of the non-woody plant fiber which is extremely easy to absorb moisture is reduced, resulting in a material having high moisture resistance and water resistance. In addition, conventional woody materials are microscopically generated at the time of nailing or sawing. It is considered that the sharp bending of the non-xylem plant fiber, which has been performed, is alleviated, and a decrease in strength around these processed portions can be prevented. Such an effect cannot be obtained with a powdery phenol resin using the same high molecular weight phenol resin or a solution phenol resin dissolved in an organic solvent.

That is, in the case of a powdery phenolic resin, it is difficult to mix the fiber and the resin. Therefore, when heated for molding, the resin easily flows and the uneven distribution thereof increases. On the other hand, in the case of a solution-type phenol resin, during the process of evaporating the organic solvent, there is no concentration of the resin at the contact points between fibers as seen in an emulsion-type resin, and therefore, it is obtained when an emulsion-type phenol resin is used. No effect occurs.

Further, a solution type phenol resin uses an organic solvent, so that it is expensive and harmful, requires a solvent recovery step, and may cause a fire or the like.

Since the water-soluble phenol resin has a low molecular weight and a large initial viscosity decrease during molding, the resin flow is large and it is difficult to obtain a good molded product, and the mechanical properties of the molded product are not satisfactory. It is easy to be. That is, a woody material using a water-soluble phenol resin is hard and brittle, and tends to be inferior in impact resistance, nailing and sawing. Further, a large amount of gas containing formalin is generated during molding, which deteriorates the working environment and requires exhaust gas treatment. When a high molecular weight phenol resin is used, almost no formalin is generated.

The phenol resin is preferably a so-called modified phenol resin. That is, by adding a small amount of a modifier to the raw phenol resin, that is, the uncured phenol resin, the phenol resin becomes a modified phenol resin during hot pressing. Here, water-insoluble polyvinyl acetate, polyvinyl alcohol,
Alternatively, acrylonitrile butadiene latex or the like can be used. That is, they are compatible with the phenolic resin at the time of the hot press treatment and improve the stress relaxation of the wood material as a product. This significantly improves the impact resistance, sawing properties and nailing properties of the wood material. In this case, the moist heat resistance and water resistance of the woody material of the product are not affected at all when the amount of the modifier is small.

In the present invention, non-timber plant fibers are fibers obtained from fiber plants, excluding xylem fibers. That is, plant fibers can be classified as follows according to the site where the plant tissue is used. Epidermal cellular fibers which are the hairs of the epidermis of seeds (cotton, milkweed etc.), thick-membrane cellular fibers which correspond to the mechanical tissues of monocotyledonous plants (such as manila, sisal hemp, ghetto, basho, bromeliad), bamboo, spruce, Wood fibers, such as fir, linden, alder, and willow; sieve fibers and bast fibers, such as flax, Asa, kouma, kasinaki, mulberry, yabumao, and ramie.

Here, it is a matter of course that the wood fibers cannot be used in view of the gist of the present invention. However, these wood fibers have a short fiber length as a fiber, so that various wood fibers are used. The mechanical performance is poor and cannot be used at all. However, it is possible to dare add a small amount for the purpose of decoration or the like. Similarly, chemical fibers, various synthetic fibers, various inorganic fibers, and the like can be used in combination for the purpose of decoration or performance improvement.

In order to obtain good mechanical properties, it is desirable to use thick-cellular fibers, bast fibers, and thick-cellular fibers having a long fiber length. Among them, bast fibers such as a timer and a jute are used. And the best results are obtained. Similar good results can be obtained with thick fibers of the mesocarp of oil palm or coconut palm, fibers derived from leaves such as agave, sisal, manila hemp, and fibers collected from kabok.

The characteristics of these non-xylem plant fibers include a long fiber length, a relatively thick fiber, and a high Young's modulus. The fiber length of the non-xylem plant fiber used is desirably 10 cm or more, and the Young's modulus is desirably 1500 kg / mm ² or more.
Woody materials produced using such non-xylem plant fibers have excellent mechanical properties.

Another characteristic is that the plant from which the xylem fiber is collected has a regeneration cycle of at least 10 years, usually 30 years, whereas it can be collected in 1 to 2 years and is easily cultivated. It is mentioned. According to the director of the Chinese Botanical Institute, it is possible to effectively produce and supply these plant fibers, which are useful to human beings, in large quantities by adopting a planned production system.

The cross section of these fibers is often a flat ribbon, and the points of contact between these plant fibers during hot pressing are not point contact but rather surface contact, and the adhesion by the resin is extremely strong. Is also a feature. Furthermore, these non-xylem plant fibers have been cultivated since ancient times and used as clothing and various materials, but due to the development and development of chemical fibers and synthetic fibers, their production is now surplus, inexpensive and extremely easily available. Is also a feature.

Here, since these non-xylem plant fibers are natural materials, they have a variation in color, and the wood material as a product also has a very good appearance. If special processing such as bleaching or dyeing is not performed, further various variations can be obtained.

In the case of hemp (timer), it is processed into hemp bags and is often used as a packaging material for imported grains, spices, coffee beans, etc., but most of it is currently disposed of as industrial waste. However, according to the present invention, its effective use becomes possible. Similarly, fabrics (bags) derived from agave are easily available. Also, coconut and oil palm fibers are generated in large quantities as by-products of collecting oils and fats, and most of them are disposed of, and these can also be used preferably.

A fibrous structure is formed from such non-xylem plant fibers as needed at the time of use. That is, a known technique such as spinning, aligning, bruising, or tying these non-xylem plant fibers into a woven fabric after forming into a thread, or into a felt shape with a former, or into a three-dimensional woven fabric. To form a fibrous structure. Moreover, you may perform combining these means. For example, needle punching may be further performed with a web-shaped plant fiber sandwiched between two woven fabrics. However, it is necessary to perform these processes by adjusting the conditions so as to keep the fiber length as short as possible. At the time of producing these fiber structures, it is also possible to use them together with bleached or dyed fibers. By passing through the fibrous structure in this way, the workability in hot pressing is improved, and the quality is stabilized, so that the mechanical properties of the wood material as a product are improved.

The fabric made from the woven fabric has a very excellent appearance and gives a high-quality impression while being natural and friendly to humans. Can add value. In addition,
The woody material of the present invention can also be applied to products with many curved surfaces such as automobile dashboards. Such a non-xylem plant fiber is immersed in an aqueous solution of an emulsion-type phenol resin, dried, and then molded by a general molding method such as pressure molding.

In the present invention, it is necessary to immerse the non-xylem plant fiber in the emulsion type phenol resin dispersion aqueous solution and then dry it. That is, by drying, the effect of using the aqueous solution of the emulsion-type phenolic resin dispersion is enhanced, and the occurrence of molding defects such as voids due to moisture during molding is prevented, and the predetermined performance is maintained. The drying is preferably performed at a temperature of 80 ° C. to 130 ° C. for 3 minutes to 20 minutes.

By removing the excess phenol resin emulsion solution with a squeezing roller or the like before dipping after the resin dispersion solution immersion, the resin content in the wood material as a product can be adjusted to a desired range. It is possible to adjust various mechanical performances, appearance or texture.

As a molding (molding treatment) method, a hot press treatment is easy, and a material having good mechanical properties can be obtained. However, those with complex shapes
It can be performed by other known means such as vacuum bag molding (autoclave molding).

The hot pressing is preferably performed at a temperature of 100 ° C. or higher and 230 ° C. or lower. If the temperature is lower than 100 ° C., the crosslinking reaction does not proceed sufficiently, and the mechanical properties tend to be poor. On the other hand, when the temperature is higher than 230 ° C., the resin flow tends to be too large, and the performance may be deteriorated due to discoloration of the product or deterioration of the fiber.

The pressing pressure is 1 kg / cm ² or more and 6
It is desirably 0 kg / cm ² or less. 1kg / c
It is difficult to obtain a wood material having excellent mechanical properties even at a pressure of less than m ² or a pressure of more than 60 kg / cm ² . That is, at a low pressure, the number of bonding points between the fibers decreases, and at a high pressure, troubles such as damage to the fibers tend to occur. In addition, those having a low resin content or those molded at low pressure have many voids and thus have low tensile and bending strength, but are suitable for applications such as sound absorbing materials and wall materials. This one also
It has good hygroscopicity and tactile sensation derived from non-xylem plant fiber, and matches the current trend of nature-oriented.

On the other hand, those having a high resin content or molded under high pressure have high strength and high density, and are suitable for furniture, building structural materials, concrete panels and the like. As described above, it is one of the many features that the characteristics of the product can be variously changed by changing the molding conditions while using the same material.

[0039]

EXAMPLES Examples of the present invention will be specifically described below. As the non-xylem plant fibers, four types of fibers shown in Table 1 are used: coconut (from the Philippines), jute (from Bangladesh), oil palm (from Malaysia), and agave (from Mexico). Each fiber was defibrated so as to have a fiber diameter of 0.1 mm to 0.5 mm, and further cut so that the fiber length was 2.5 cm to 15 cm. The basis of the web of these fibers is 26
After laminating to 40 g / m ² , felts A, B, C and D were respectively produced by a former. In addition, the cutting of these fibers did not occur by this felting. The Young's modulus shown in Table 1 is an average value of 10 samples collected near the center in the length direction of each fiber.

[0040]

[Table 1]

Five kinds of resin compositions as shown in Table 2 (resin 1 was an unmodified emulsion type phenolic resin, and resins 2 and 3 were polyvinyl acetate emulsion resins, Polysol 1200 manufactured by Showa Polymer Co., Ltd.) were added and mixed. The modified emulsion-type phenolic resin obtained by the above method was modified such that resins 4 and 5 obtained by adding and mixing Hiker 1571 manufactured by Nippon Zeon, which is an acrylonitrile-butadiene latex), each having a solid content of 25% by weight. And then used as an aqueous emulsion dispersion solution.

[0042]

[Table 2]

The felts A to D (3
(0 cm × 30 cm square), and excess resin was removed with a squeezing roller. The resin removal by the squeezing roller was adjusted so that the resin content measured after drying at 100 ° C. for 15 minutes was 58 g to 60 g,
Resin impregnated felts A1-A5, B1-B5, C1-C5
And D1 to D5 were obtained.

On the other hand, using the felts A to D similarly cut into squares having a side length of 30 cm, the above five emulsion dispersion aqueous solutions were sprayed to obtain a resin content of 58 g to 60 g after drying. Then, drying was performed at 100 ° C. for 15 minutes to obtain resin impregnated felts A6 to A10, B6 to B10, C6 to C10, and D6 to D10.

These resin-impregnated felts were subjected to a hot press treatment at 170 ° for 6 minutes to obtain wooden material plates A1 to A10, B1 to B10, C1 to C10, and D of 0.6 cm thick.
1 to D10 were obtained. No formalin odor was generated during the molding. In addition, the appearance of the manufactured wooden material plate was all good, had a soft impression derived from the raw material fibers and a moderate moisture absorption, and gave a gentle impression.

The wooden material plate produced as described above was evaluated. First, the bending strength and bending Young's modulus of these molded plates were examined in accordance with the JAS structural plywood standard. As for molded plates made of the same fiber and the same resin, the resin impregnation was carried out by immersion. There was no significant difference between those obtained by spraying and those obtained by spraying.

Next, the thickness change upon swelling (JIS A59)
05), and nailability was evaluated. In other words, regarding the thickness change at the time of swelling, as "the thickness change at the time of swelling"
When the thickness after swelling is 100%, the rate of increase in swelling is 10% or less: ◎: More than 10%, 20% or less: 、, More than 20%: 50% or less, Δ: More than 50% It evaluated as x. On the other hand, the nailing property was 12 mm in length and 1.
A 6 mm nail was hit three times with a hammer and the state of being driven into the wooden material plate was evaluated. At this time, when the nail was completely driven in, ◎ when 50% or more of the nail length was driven in, and when less than 50%, △, and when the wooden material plate was cracked ×, and xx if further omissions occur
Was evaluated.

Further, the wood screw holding ratio was determined in accordance with JIS A5906.
Investigated according to. At this time, ◎ indicates a case of 50 kgf or more, and ○ indicates a case of less than 50 kgf and 40 kgf or more.
30 kgf or less of less than gf was evaluated as Δ, and less than 30 kgf was evaluated as x. On the other hand, the sawing property was evaluated as follows. Observe the cut part when cutting the above-mentioned wooden material plate using an electric saw for wood, ◎ when the cut part is in a clean state without breakage and missing, and when there is slight jagged, but generally good, ○も の, those with apparent jaggedness, and those with cracks or missing parts in the cut part
Was evaluated.

The ease of deformation such as warpage after molding was evaluated as “strain after molding” using a separately produced molded product as follows. A molded product as shown in FIG. 1 is molded in the same manner as the above-mentioned woody material plate, except that the treatment temperature is 170 ° C., the treatment time is 8 minutes, and the pressing pressure is 15 g / cm ² , and this is placed on a platen. At this time, make sure that all four corners are in contact with the surface plate, and leave it indoors for 15 days. Thereafter, the maximum floating distance from the surface plate was measured. Tables 3 to 6 show these results.
Shown in

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

When these wood materials were burned in small quantities, assuming the final disposal by incineration, the wood materials had little odor and smoke.

From these results, it can be seen that the woody material of the present invention has excellent bending strength and bending Young's modulus without using wood which may be depleted, and further has nailing property, sawing property, wood screw retention rate, and water resistance. It is found that the material is excellent in heat resistance and moisture resistance, hardly generates warpage, bending, and warpage, and can be easily disposed of by incineration.

[0056]

The wood material according to the present invention can be made in various shapes, is inexpensive, is easy to manufacture, and does not have a natural touch to the person in contact with it, while eliminating the need for wood resources, which are concerned about depletion. It is an excellent material that gives an impression, is excellent in moisture resistance, water resistance and processability, is non-polluting, easy to dispose of finally, and does not generate NOx gas and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of a sample for checking the occurrence of warpage.

Claims (7)

[Claims] 1. A fiber structure composed of non-xylem plant fibers is immersed in an aqueous solution of an emulsion-type phenol resin dispersion,
A wood material characterized by being formed after drying. 2. The woody material according to claim 1, wherein an excess amount of the aqueous resin dispersion contained in the fibrous structure immersed in the aqueous emulsion type phenolic resin dispersion is removed before drying. material. 3. The wood material according to claim 1, wherein a modifying component for modifying a phenol resin is added to the aqueous emulsion resin dispersion. 4. A fiber structure composed of non-xylem plant fibers is immersed in an aqueous solution of an emulsion type phenol resin,
A method for producing a woody material, comprising forming after drying. 5. The method according to claim 5, further comprising the step of removing an excess of the aqueous resin dispersion contained in the fibrous structure immersed in the aqueous emulsion type phenol resin dispersion before drying. Method of manufacturing woody material. 6. The method for producing a wood material according to claim 4, wherein a modifying component for modifying the phenol resin is added to the aqueous emulsion-type phenol resin dispersion solution. 7. The method for producing a woody material according to claim 4, wherein the molding step is performed by a hot press method.