JPH01196301A - Timber impregnated with resin - Google Patents

Abstract

PURPOSE:To satisfy both resistance to hygroscopic power and resistance to swelling power and dimension stability by applying either tert-butyl cyclohexyl (metha)acrylate and a mixed monomer composed of said component and another monomer copolymerizable with said and component polymerizing. CONSTITUTION:Monomers with which a timber is impregnated consist of a component (a) composed of one or both of tert-butyl cyclohexyl acrylate or tert-butyl cyclohexyl methacrylate and a component (b), a mixed monomer composed the monomer of said component (a) and a mixed monomer composed of another monomer copolymerizable with the monomer of component (a), and 5% or more of the monomer of component (a) to the whole of monomer is included. As the component (a) is of high lipophilic nature containing a cyclic, bulky radical with a number of carbons in its molecule, both resistance to hygroscopic power and resistance to swelling power of a resin impregnated timber are good, and cracks and warps therein are controlled to offer superior dimension stability.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to tert-butylcyclohexyl acrylate or tert-butylcyclohexyl methacrylate [hereinafter referred to as acrylate and methacrylate together (
This invention relates to resin-impregnated wood whose dimensional stability has been improved using meth)acrylate.

[Conventional technology]

In general, wood has the property of swelling and contracting when it absorbs and releases moisture, and this has the disadvantage of causing warping and cracking. The reason for this is that when moisture in wood moves, it evaporates first near the surface of the wood, causing drying shrinkage, but inside the wood the moisture content is still high and does not shrink. It is thought that stress is generated at the boundary between dry shrinkage and non-shrinkage, and that warping and cracking occur in an attempt to alleviate this stress.

Conventionally, methods such as formalization, acetylation, cyanoethylation, and alkyl ketene dimer treatment have been known to prevent these phenomena and improve the dimensional stability of wood. However, it is not practical because the wood becomes brittle or the process is complicated, making it difficult to implement and increasing costs considerably.

On the other hand, polyethylene glycol treatment and monomer impregnation methods have also been proposed. The former method involves impregnating and filling the voids in wood with polyethylene glycol. In addition, the latter method involves impregnating a polymerizable monomer into the voids of wood and polymerizing it, and this method has the characteristic that it can particularly improve the physical properties of wood such as hardness, tensile strength, and bending strength. There is.

[Problem to be solved by the invention]

However, among the above-mentioned proposed methods, the former polyethylene glycol treatment contributes to reducing the swelling property when absorbing moisture, that is, improving the anti-swelling ability, and brings good results to the dimensional stability of wood, but polyethylene glycol is hydrophilic. Therefore, the polyethylene glycol, which is orally hydrophilic and has a relatively low molecular weight, is easily eluted onto the wood surface and causes phenomena such as wetting and bleeding of the wood surface. However, in this case, there was a problem that the paintability of various paints, which are usually used to protect the wood, would be significantly deteriorated.In addition, in the monomer impregnation method, methyl methacrylate, styrene, etc. , hydroxyethyl methacrylate, polyalkylene glycol monomethacrylate, etc., but among these, those using hydrophilic monomers do not have enough anti-hygroscopic properties as in the case of the polyethylene glycol treatment described above. <
On the other hand, when using methyl methacrylate or styrene, which have relatively good anti-hygroscopic properties, the anti-swelling properties are poor and it is difficult to obtain good results in improving dimensional stability.

In view of the problems of the prior art as described above, the present invention aims to obtain resin-impregnated wood that satisfies both moisture absorption and swelling resistance and has significantly improved dimensional stability.

[Means to solve the problem]

As a result of intensive studies to achieve the above object, the present inventors have found that by using a specific monomer that has not been used conventionally as an impregnating monomer in the monomer impregnation method, this monomer can be impregnated and polymerized. The anti-hygroscopic ability and anti-swelling ability of the wood are both satisfactory.
It was discovered that excellent dimensional stability and good paintability can be obtained, and the present invention was completed.

That is, the present invention provides wood with any of the following components a and b; a) tert-butylcyclohexyl (meth)acrylate b) a monomer mixture consisting of component a and other monomers copolymerizable therewith. There is also a resin-impregnated wood made by impregnating and polymerizing wood.

As for the wood used in the present invention, there is no need to distinguish between softwood, hardwood, domestic wood, and foreign wood. Also,
Depending on the purpose, it can be applied to all types of wood such as raw wood, logs, square pillars, cylinders, and sawn boards.

In the present invention, the monomer of component a to be impregnated into the wood is tert-butylcyclohexyl (meth)acrylate, that is, either or both of tert-butylcyclohexyl acrylate and tert-butylcyclohexyl methacrylate. These monomers can be synthesized, for example, by esterification reaction of ter't-butylcyclohexyl alcohol and acrylic acid and/or methacrylic acid, and are also available as commercial products.

In addition, in the present invention, the monomer of the above-mentioned component to be impregnated into the above-mentioned wood is a mixed monomer consisting of the monomer of the above-mentioned component a and another monomer copolymerizable with the monomer, of which the monomer of the above-mentioned component a is entirely Usually 5 in monomer
The proportion is set to be at least 20% by weight, preferably at least 20% by weight. If the amount of monomer (a) is too small, it becomes difficult to obtain wood with excellent dimensional stability and paintability that satisfies the effects of the present invention, that is, anti-hygroscopic ability and anti-swelling ability, which is not preferable.

Other copolymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, Tetradecyl (meth)acrylate,
Linear alkyl (
branched alkyl (meth)acrylates such as meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isostearyl (meth)acrylate;
Alkenyl (meth)acrylates such as oleyl (meth)acrylate, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, diethylene glycol, Dipropylene glycol, tripropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, etc. with 2 or more carbon atoms
(meth)acrylate of polyalkylene glycol which is a 2 to 100 molar condensate of alkylene glycol of No. 4;
Examples include styrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, glutaryl (meth)acrylate, glycerol (meth)acrylate, trimethylolpropane (meth)acrylate, and pentaerythritol (meth)acrylate.

In the present invention, either one of the above components a and b, that is, tert-butylcyclohexyl (meth)
Acrylate is impregnated into wood either alone or in a mixed system with other monomers that can be copolymerized with it. At this time, these monomers may be impregnated into wood as they are,
The impregnation may be carried out as a solution dissolved in an organic solvent.

Examples of the organic solvent used here include solvents such as methanol, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, toluene, xylene, and cyclohexane.

In addition, other additives such as preservatives, insect repellents, ultraviolet absorbers, etc. may be added to the monomer for impregnation or the solution obtained by dissolving the monomer in an organic solvent, if necessary. Furthermore, monomers, oligomers, polymers, etc. that are soluble in organic solvents can also be added.

To obtain resin-impregnated wood by impregnating wood with the above monomer or its solution and polymerizing it, for example, first seal the wood in a container, reduce the pressure inside the container with a vacuum pump, etc. Inject the monomer or its solution,
Thereafter, the wood is brought to an atmospheric pressure or pressurized state, and the above monomer or its solution is impregnated into the voids of the wood. When an organic solvent is used, after this impregnation, a drying treatment such as natural drying, heat drying, or reduced pressure drying is performed to remove only the organic solvent from the wood. The monomer impregnated into the wood is then polymerized.

The polymerization method is not particularly limited, and examples include a method of heating and polymerizing monomer-impregnated wood in a heating furnace in a state where oxygen is blocked such as in nitrogen gas, a method of performing radiation polymerization using radioactive cobalt 60, etc. A polymerization initiator such as a peroxide such as benzoyl peroxide or methyl ethyl ketone peroxide or a combination thereof with a reducing agent such as cobalt naphthenate or dimethylaniline is added to the above-mentioned impregnating monomer or its solution. A method of polymerization, a method using a combination of peroxide and an electron beam, etc. can be applied.

The resin-impregnated wood according to the present invention obtained in this way is
The polymer retention rate is generally about 5 to 250% by weight, or about 5 to 150% by weight. The above-mentioned polymer retention rate means the weight ratio of the polymer to the wood of the resin-impregnated wood, that is, the value calculated by the following formula.

X: Absolute dry weight of resin-impregnated wood Y: Absolute dry weight of untreated wood [Function] The tert-butylcyclohexyl (meth)acrylate used in the present invention has a bulky alicyclic group with a large number of carbon atoms in its molecule. Since it is highly lipophilic, wood impregnated and polymerized with this material exhibits high water repellency, and as a result, the hygroscopicity of the wood is significantly reduced, in other words, it is thought that a high anti-hygroscopic ability can be obtained. It will be done.

In addition, because the monomers mentioned above have bulky substituents as mentioned above, they have less volumetric shrinkage during polymerization than conventional methyl methacrylate or styrene, and this reduces the internal stress of the wood when it absorbs moisture. It is thought that the swelling of the resin is suppressed, that is, a high anti-swelling ability is obtained.

Furthermore, the above monomers can be polymerized in wood by
Unlike traditional polyethylene glycol impregnation filling, this polymer is orally eluted onto the wood surface after polymerization to provide a lipophilic polymer with a high molecular weight, high glass transition temperature, and bulky structure. There is no particular risk.

〔Effect of the invention〕

As described above, the resin-impregnated wood according to the present invention has good anti-hygroscopic ability and anti-swelling ability, and has excellent dimensional stability with suppressed cracking and warping caused by moisture swelling and moisture releasing shrinkage peculiar to wood. Furthermore, since there is no risk that the impregnating resin will be orally eluted onto the surface of the wood, there will be no problem of impairing subsequent paintability.

Therefore, the resin-impregnated wood according to the present invention is particularly suitable as an exterior wall material that is constantly affected by moisture and dryness, such as flooring materials, wooden works of art, and building materials that require a high degree of low dimensional stability. Moreover, it can be widely used for various purposes other than these.

[Examples] Next, Examples of the present invention will be described in more detail.

Examples 1 to 4 Six types of resin-impregnated wood according to the present invention were obtained by the following method using the treatment liquids listed in Table 1 below for wood impregnation. First, a test material (produced in Shizuoka Prefecture) cut to a size of 3 ON in the tangential direction, 30 fi in the radial direction, and 70 m in the fiber direction was depressurized to 10 mHg in a desiccator for 5 minutes. Next, pour the treatment liquid into a desiccator and return it to normal pressure.
It was left for 4 hours. Thereafter, it was taken out from the desiccator and air-dried at room temperature. This impregnated wood was wrapped with aluminum foil and heated and polymerized in a heating oven at 80° C. for 24 hours to obtain resin-impregnated wood. The polymer retention rate of each wood obtained was as shown in Table 1.

In addition, t-BCHMA in the treatment solution in Table 1 is te
rt-butylcyclohexyl methacrylate, t-B
CHA represents tert-butylcyclohexyl acrylate, ADMVN represents 2,2'-azobis-2,4-dimethylvaleronitrile, and AIBN represents 2,2'-azobisisobutyronitrile.

Comparative Examples 1 to 4 Four types of resin-impregnated wood were obtained in the same manner as Examples 1 to 4, except that the treatment liquid listed in Table 1 was used as the treatment liquid for wood impregnation. However, in Comparative Example 4 using polyethylene glycol, the polymerization treatment in a heating oven was not performed. The polymer retention rate of each wood was as shown in Table 1.

The moisture absorption rate and volumetric swelling rate of each resin-impregnated wood of the above Examples and Comparative Examples were measured, and the anti-hygroscopic ability (MEE) and anti-swelling ability (ASE) of the treated materials were calculated from these measured values.The results are described below. It is shown in Table 2.

Note that the moisture absorption rate and volumetric swelling rate were measured by the following methods.

Moisture absorption rate> Resin-impregnated wood as an absolutely dry sample was dried at 20°C and relative humidity 9.
Weight (Xt) after absorbing moisture in a 3% atmosphere
The moisture absorption rate was calculated from the absolute dry weight (X) before moisture absorption using the following formula.

<Volume swelling rate> Resin-impregnated wood as an absolutely dry sample was heated at 20°C and relative humidity 9
The volume (ML) after absorbing moisture in a 3% atmosphere
The volumetric swelling rate was calculated from the volume (M) before moisture absorption using the following formula.

ML-M Volume swelling rate (%') = X100 Also,
Anti-moisture absorption capacity (MEE) and anti-swelling capacity (ASE) are determined by measuring the moisture absorption rate and volumetric swelling rate of untreated wood in the same manner as in the case of resin-impregnated wood, and comparing this with the moisture absorption rate and volumetric swelling rate of resin-impregnated wood. It was calculated from the following formula. Needless to say, the following values of anti-hygroscopic ability (MP) and anti-swelling ability (ASE) indicate that the larger these values are, the better the properties of the wood are.

Wc: Moisture absorption rate of untreated wood Wt; Moisture absorption rate of resin-impregnated wood ■c: Volumetric swelling rate of untreated wood ■t: Volumetric swelling rate of resin-impregnated wood Note that the number of days left in the measurement of moisture absorption rate and volume ratio is as follows:
Although the measurements were taken for 1 day, 5 days, and 15 days, respectively, the moisture absorption rate and volume swelling rate calculated under the above measurement conditions generally reach equilibrium after about 2 weeks.

Table 2 As is clear from the results in Table 2 above, those using methyl methacrylate or styrene as monomers for wood impregnation (Comparative Examples 1 and 2) have relatively good moisture absorption ability (MEE). , the anti-swelling ability (ASE) was decreased, which is thought to be due to water vapor entering the details of the wood and increasing its volume.

In addition, in the case of using polyethylene glycol monomethacrylate as the monomer for wood impregnation (Comparative Example 3) and the case of simply impregnating and filling with polyethylene glycol (Comparative Example 4), the anti-swelling ability was good, but the anti-hygroscopic ability was poor. This is because the impregnated polymerized resin and polyethylene glycol have strong hydrophilic properties.

In addition, these Comparative Examples 3 and 4 have poor moisture absorption ability,
Wetness and bleeding were observed on the wood surface upon moisture absorption, and this tendency was particularly noticeable in Comparative Example 4.

In contrast, Example 1 is Comparative Example 1 in cedar sapwood.
From comparison with Comparative Example 2, it can be seen that the anti-hygroscopic ability is the same or higher, the anti-swelling ability is large, and the dimensional stability is excellent. In addition, Example 2 in which the concentration of tert-butylcyclohexyl (meth)acrylate in the treatment liquid was lowered
-4, the anti-hygroscopic ability is slightly lower than that of Example 1, but the anti-swelling ability after 5 days and 15 days is almost unchanged and good dimensional stability is maintained. In addition, in all of these Examples 1 to 4, the phenomenon of bleeding due to moisture absorption did not occur, and no problems occurred in normal painting.

Patent applicant: NOF Corporation

Claims (1)

[Scope of Claims] 1) A mixture of the following components a and b in wood; a) tert-butylcyclohexyl acrylate or tert-butylcyclohexyl methacrylate b) a mixture of the above component a and other monomers copolymerizable therewith; Resin-impregnated wood that is impregnated with any of the monomers and polymerized.