JPH04278303A - Manufacture of resin treated ligneous material - Google Patents

Abstract

PURPOSE:To provide resin impregnated ligneous based material, which represents the external appearance intrinsic to ligneous material and, at the same time, is excellent in dimensional stability, stain resistance, handling characteristics and workability. CONSTITUTION:Aqueous phenolic resin solution, which is prepared so as to bring the pH of the solution to 3-7 by mixing proper amount of acid such as toluenesulfonic acid, benzenesulfonic acid or the like with water and contains 40wt.% or less of nonvolatile content, is infiltrated in the ligneous material so as to infiltrate the aqueous phenolic resin solution diluted with a large number of water in the cell wall of the ligneous material. Next, by volatilizing water content infiltrated in the ligneous material, the pH is brought to below 3 so as to make the phenolic resin more sticky in order to prevent the resin from flowing out of the ligneous material and, at the same time, the resin is hardened under relaxed condition so as to prevent the ligneous material from coloring and its brittleness from lowering.

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 resin-treated wood material that has excellent dimensional stability, durability, stain resistance, workability, etc., and exhibits the appearance of wood.

0002

[Prior Art] Modified phenol has traditionally been used to improve dimensional stability, strength, etc., which are the shortcomings of wood, by injecting and filling phenolic resin liquid into the fine voids in the cell walls of wood. Resin injection treated wood materials are known.

0003

[Problems to be Solved by the Invention] However, according to the conventional method for producing wood materials injected with phenolic resin, the coloring components of the phenol resin and wood become colored, and there is also a difference in thermal deterioration of the wood and expansion and contraction of the injected resin. The problem is that the wood becomes brittle due to shrinkage, cracks and warping occur, and gaps are created between the cured resin and the wood cell wall surface, making it easier for contaminants to enter.

[0004] Therefore, when attempting to relax the curing conditions of phenolic resin using various catalysts, the phenol resin liquid injected into the wood material aggregates and becomes highly viscous, preventing it from penetrating into the fine pores of the wood material, resulting in a reduction in the modification effect. There were problems such as the catalyst was small and the wood material was contaminated by the catalyst.

[0005] The present invention was made in view of the above problems, and has a structure in which the phenolic resin is injected and cured with almost no coloration, the original appearance of the wood is maintained, the wood does not become brittle, and it has excellent cutting properties and light weight. The present invention provides a method for producing a resin-treated wood material that exhibits comprehensively excellent physical properties such as dimensional stability, durability, and stain resistance.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the method for producing resin-treated wood materials of the present invention includes adding acids such as toluenesulfonic acid, benzenesulfonic acid, boric acid, and phosphoric acid. By impregnating wood with a phenolic resin aqueous solution with a non-volatile content of 40% by weight or less and adjusting the pH to 3 to 7, and heating the wood to a temperature at which the resin can be cured, the water is evaporated and the resin is cured. This makes it easier for the resin liquid to penetrate.

[0007]

[Action] Since the non-volatile content of the phenolic resin aqueous solution is 40% or less, and the pH is kept at 3 to 7 even when an organic acid is added, water suppresses the condensation reaction of the resin and reduces the viscosity of the phenolic resin aqueous solution, which is the treatment liquid. The treatment solution easily penetrates into the cell walls of wood materials, which are hydrophilic. Also, pH
Since it is set to 3 or more, acid contamination of wood materials can also be prevented. After the phenol resin aqueous solution to which an acid has been added is injected into the wood material, it is heated to evaporate water and the phenol resin begins to increase in viscosity. Furthermore, the resin hardens when heated, but if the pH is below 7, darkening of the phenol resin and coloring of the wood will be prevented.
The treated wood will not be colored and will not become brittle.

[0008]

[Example] Next, to describe an example of the present invention in detail, an appropriate amount of acid was added to an aqueous phenol resin solution whose nonvolatile content was adjusted to a concentration of 1 to 40% by weight by adding an appropriate amount of water. 7. Prepare the injection treatment solution. In addition, as acids, toluenesulfonic acid, benzenesulfonic acid,
Acids such as phenol sulfonic acid, xylene sulfonic acid, oxalic acid, boric acid, phosphoric acid, etc. can be used, and if the pH is less than 3 with acids alone, an alkali such as sodium hydroxide, potassium hydroxide, etc. can be used to prevent gelation. Adjust the pH by mixing metal hydroxides and amines such as dimethylamine.
Adjust to 3-7.

[0009] Next, the treatment liquid is injected into the wood material. This injection method is carried out by reduced pressure or pressure injection, but it can also be carried out by immersion, which is suitable for the shape and size of the wood, permeability, and tree species so that the synthetic resin aqueous solution is evenly injected and impregnated into the wood. The method and conditions may be selected as appropriate. Furthermore, the wood material to be injected may be any of thick sawn timber products such as square timber, board timber, and hollow timber, laminated timber, plywood, and thin boards such as veneer, and the species of the wood is not particularly limited.

When the treatment solution is injected into wood using such an appropriate injection means, the phenol resin aqueous solution contains a large amount of water and has been adjusted to pH 3 to 7, so it is difficult to At the time of injection, the water suppresses the increase in viscosity of the acid and phenol resin in the treatment liquid, prolonging the pot life of the treatment liquid, and allowing the treatment liquid to easily penetrate into the cell walls of the hydrophilic wood material. In addition, if the pH is less than 3, not only the viscosity of the resin increases, but also discoloration of the wood material occurs, which is not preferable. Moreover, if the pH exceeds 7, the treated wood material may become discolored or brittle, which is not preferable.

After injecting the treatment liquid into the wood material, the resin-infused wood material is heated with a hot air dryer. In addition,
As the heating and drying means, high frequency heating, a hot plate, etc. may be used, and reduced pressure drying means may be employed. When the treatment solution is heated in this way, most of the water contained in the treatment solution in the wood is released out of the wood mainly through large cavities such as the cell cavities of the wood, resulting in voids (intracellular cavities) that are not filled with resin. is formed, while small voids within the cell wall are filled with resin.

[0012] At this time, the acidity of the treatment liquid containing an acid is increased by removing water, but in order to smoothly carry out the reaction with the phenol resin, the pH is lowered to less than 3. In this way, the p
The reaction between the acid and the resin starts gradually due to the decrease in H.
The viscosity of the phenol resin begins to increase, and the outflow of resin liquid decreases.

Next, the phenol resin was cured at a temperature of 40 to 1
This is carried out at 50°C for several minutes to several hours. In addition, in such resin curing treatment, the resin is completely cured under a treatment condition of 120° C. or lower under reduced pressure. At this time, if the heat treatment is performed and the curing reaction of the phenol resin is performed at a pH of less than 3, the coloring and brittleness of the coloring component of the wood material are suppressed, and the phenol resin is prevented from becoming darker in color.

As a result, the cell cavities, which are large cavities within the wood, are hardly filled with resin and become hollow, and the resin is injected into the small cavities within the cell walls and hardened, giving the appearance of natural wood. The result is treated wood with a color that maintains its original color. Note that the presence of an acid changes the molecular structure of the phenol resin, reducing the yellow tinge of the phenol resin and making it lighter in color, thereby preventing darkening.

[0015] If the resin filling rate in the voids of the wood material becomes high, problems such as coloring and cost increase due to the phenol resin will occur, so it is important to keep the concentration of the phenol resin aqueous solution within the above range of 40% by weight or less. It is for making adjustments.

[0016] Furthermore, as is clear from the test results below, even if the wood species of the tree has a specific gravity of 0.3 to 0.5, the dimensions can be improved by injecting a phenolic resin aqueous solution with a concentration of 10 to 25% by weight. Modifying effects such as stability can be achieved, so even with wood materials with poor resin injectability or wood materials with a high specific gravity of 0.8, by injecting a phenol resin aqueous solution with a concentration of 40%, the dimensional stability and stability can be improved. This makes it possible to improve stain resistance.

Next, specific examples and experimental examples of the present invention will be shown. Example 1 A hemlock veneer with a thickness of 8 mm, a width of 10 cm, and a length of 1 m,
By adding 0.5% by weight of para-toluenesulfonic acid, p
A phenolic resin aqueous solution with a resin non-volatile content of 10% by weight adjusted to H5 was heated at 5Kg/cm for 30 minutes under a reduced pressure of 40 torr.
Decompression/pressure injection was carried out for 30 minutes under the pressure of 2. Next, this resin-injected veneer was heated in a hot air dryer at 60°C to remove moisture, and then the injected resin was reacted and cured in a hot air dryer at 105°C for 12 hours. The thus obtained treated veneer had an appearance in which the redness and burnt characteristic of conventional phenolic resins disappeared and the color tone before treatment was maintained. Furthermore, even when this treated veneer was exposed outdoors for 45 days, stains were hardly noticeable and it had excellent stain resistance.

Comparative Example 1 In Example 1, the amount of para-toluenesulfonic acid added was 0.05%, the pH was adjusted to 7.5, and the curing temperature was set to 1.
Comparative Example 1 was obtained by performing the same operation as in Example 1 except that the temperature was 50°C. The treated veneer thus obtained had a red color.

Experimental Example 1 The impact bending strength of Example 1 and Comparative Example 1 together with the untreated material was measured in an air-dried state and in a water-injected state, and the effect of preventing brittleness was tested. As a result, as is clear from Table 1 below, although the Comparative Example was weakened to 1/2 that of the untreated wood, the Example 1 was found to have the same toughness as the untreated wood. Therefore, it has been found that the defects of phenolic resin-treated wood, which has conventionally been prone to corner chipping, can be significantly improved.

[0020]

[Table 1]

[0021]

Effects of the Invention As described above, according to the method for producing resin-treated wood materials of the present invention, acid is added and the pH is 3 to 7.
This method is characterized by impregnating a wooden material with an aqueous solution of phenolic resin having a non-volatile content of 40% by weight or less and heating the wooden material to a temperature at which the resin can be cured to volatilize water and cure the resin. Since the pH is adjusted to 3 to 7 and a large amount of water is present in the phenol resin aqueous solution, it maintains a low viscosity even in the presence of acids and easily penetrates into the small voids in the cell walls of wood materials. Not only can it be impregnated with an aqueous solution of phenolic resin, but heating after this impregnation treatment starts to increase the viscosity of the phenol resin, hardening it in a state that makes it difficult for the phenol resin to flow out from minute voids in the cell wall. It is something that can be done.

Furthermore, by heating, the presence of an acid can ease the curing conditions of the phenol resin, such as curing temperature and time, suppressing the coloration of the coloring component of the wood material and the decrease in toughness, and the acid also suppresses the curing conditions of the phenol resin. Darkening can be prevented. In addition, even if an acid is added when preparing a treatment liquid, the phenol resin aqueous solution is prevented from condensation polymerization by a large amount of water before treatment, making it easier to maintain pot life and adjust viscosity. Furthermore, since the method uses heating to volatilize water and harden the resin, it is possible to perform the work continuously using the same equipment.

[0023] Therefore, the phenol resin injected into the cell walls of the wood material and cured can prevent moisture and contaminants from entering the wood material, improving dimensional stability, stain resistance, and
It is possible to improve the antiseptic and insect repellent properties. Furthermore, since the wood material remains porous with large voids such as intracellular cavities, it is possible to prevent discoloration unlike the conventional manufacturing method of resin-treated wood materials in which the voids are filled with resin. It is possible to obtain a wood material that maintains the original appearance of natural wood materials and exhibits excellent cosmetic properties, and also to produce a wood material that is excellent in cutability and lightness.

Claims (1)

[Claims] [Claim 1] Contains an acid and has a pH of 3 to 7.
A resin-treated wood characterized by impregnating a wooden material with a phenolic resin aqueous solution with a non-volatile content of 40% by weight or less and heating the wood to a temperature at which the resin can be cured to volatilize water and cure the resin. Method of manufacturing wood.