【発明の詳細な説明】[Detailed description of the invention]
産業上の利用分野
本発明は木材、特に南洋材の防虫剤に関するも
のである。
従来の技術
最近、ラワン材等南洋材の防虫には木材にホウ
素化合物およびフツ素化合物の水溶液を加圧また
は減圧注入する方法が広く用いられるようになつ
てきた。
これらの化合物は製材の日本農林規格で防虫剤
として認められており、その防虫作用は広く知ら
れている。
かかるホウ素系の薬剤としてはホウ砂とホウ酸
の混合物または８ホウ酸ナトリウム４水和物が広
く使用されている。その理由は安全性が高く、安
価であつて、水溶性であるので取扱いが簡単であ
り、さらに加圧処理装置に対する腐蝕性がない等
である。
発明が解決しようとする問題点
しかしながら、ホウ砂とホウ酸の混合物、また
は８ホウ酸ナトリウム４水和物で南洋材を加圧、
防虫加工すると辺材と心材の移行部に赤〜赤紫色
の着色を起す材がある。特にサバ産の白色系材に
多発している。
この着色は加工直後よりも乾燥途中から認めら
れ、特に日光に曝露されるとさらに着色度が増
す。このため防虫加工後の材の商品価値を低下さ
せ問題となつている。
処理液のPHがアルカリ側で着色度が強く、空
気、日光によつてさらに強調されることが確認さ
れた。
現在のところ着色する材を事前にチエツクし選
別する技術も確立されていない。
従つて、防虫薬剤（処理液）が着色を防止する
性能を持たなければならなくなつた。そこでホウ
砂とホウ酸の配合割合を変えるか、または酸性成
分を添加することにより処理液のPHを下げること
で着色度は軽減されるが、完全でなく、さらにPH
が中性以下にまで低下すると加圧装置が鉄製のた
め腐蝕を起す。と同時に処理液中に鉄イオンが出
てくるため、この鉄イオンと材中のタンニン様物
質とが反応する。従つて処理液が暗色化し、処理
材も黒く仕上る。
問題点を解決するための手段
前記の如き処理材の着色を防止するには次の方
法が考えられる。
(イ) 前処理を行うことにより着色を防止する。
(ロ) 後処理を行うことにより着色した材をきれい
にする。
(ハ) 処理液に着色防止剤を添加する。
(ニ) 薬剤に着色防止剤を混合しておく。
しかしながら、(イ)、(ロ)の方法は２回の工程にな
り不利である。
さらに(イ)の方法では表面処理であり、後で加圧
処理されるため効果がなくなる。(ロ)の方法では一
度変色した材にはかなり強い処理が必要である。
また一梱包全部が着色するわけではないため結束
をほどく必要も生じる。などの理由から(ハ)と(ニ)の
方法について検討した結果、(ハ)の方法よりも(ニ)の
方法の方がより簡易で経済的であること、および
着色防止剤として次の条件を満たす必要があるこ
とがわかつた。
(a)水溶性である。
(b)ホウ酸と併用できる。
(c)材を着色しない。
(d)安全性が高く、取扱いが容易である。
(e)アルカリ性でありPH調整に使える。
(f)鉄腐蝕を起さない。
(g)処理材からのホウ酸の定量に影響しない。
(h)処理液中のホウ酸の濃度測定に影響しない。
(i)安価である。
本発明者らは前記の結果から防虫効果は勿論の
こと、防虫加工を行うことによる処理材の着色を
防止しうる木材防止材について研究した結果、薬
剤としてのホウ酸に着色防止剤としてリン酸の塩
類を併用することにより、防虫効果に加えて処理
材の着色を防止し、さらに加圧または減圧等の処
理装置の金属腐蝕も抑え、処理液の汚損をも軽減
できることを見い出した。
すなわち本発明の目的はホウ酸とリン酸の塩類
とを主成分として含む木材防虫材を提供すること
である。
本発明に使用するホウ酸は白色の結晶性粉末で
水に溶解すると弱い酸性を示す。製材のJASの防
虫処理では処理材の辺材中にホウ酸として0.3％
以上含まれていればヒラタキクイムシに対する防
虫効果が得られると規定されている。
また本発明に使用するリン酸の塩類としてはリ
ン酸２水素ナトリウム、リン酸水素２ナトリウ
ム、リン酸３ナトリウム、リン酸２水素カリウ
ム、リン酸水素２カリウム、リン酸３カリウム、
リン酸２水素アンモニウム、リン酸水素２アンモ
ニウム、リン酸３アンモニウム、トリポリリン酸
ナトリウム、ピロリン酸カリウム、ヘキサメタリ
ン酸ナトリウム、ピロリン酸ナトリウムなどがあ
げられるが、特にアンモニウム塩類が特に好まし
い。
これらのリン酸の塩類は水に溶解したとき、
各々の性質によつて酸性〜アルカリ性を示すが本
発明の木材防虫剤のPH調整をする場合、単独また
は２つ以上のものを組み合わせ使用することは可
能である。
本発明の木材防虫剤は前記の如きホウ酸および
リン酸の塩類からなるが、これらの配合比はホウ
酸70〜95重量％、リン酸の塩類５〜30重量％が好
ましい。ホウ酸が前記配合比よりも過小になれば
防虫効力が懸念され、また過大であればリン酸の
塩類の種々の効果に影響を与える。すなわち中性
附近へのPH調整、金属腐蝕防止等の効果が失われ
る。
本発明の木材防虫剤を実際に木材に加工する際
は、ホウ酸およびリン酸の塩類、必要により他の
防虫剤、防カビ剤等を同時にまたは別々に水に溶
解して常法により加圧（または減圧）注入処理を
行う。
以下実施例、試験例を挙げて本発明を具体的に
説明するがこれらに限定するものではない。
実施例 １
ホウ酸85重量部とリン酸水素２アンモニウム15
重量部を混合して本発明の木材防虫剤を得た。
実施例 ２
ホウ酸90重量部とリン酸水素３アンモニウム10
重量部を混合して本発明の木材防虫剤を得た。
実施例 ３
ホウ酸85重量部とリン酸水素２ナトリウム15重
量部を混合して本発明の木材防虫剤を得た。
比較例 １
ホウ酸70重量部とホウ砂30重量部を混合して木
材防虫剤を得た。
比較例 ２
ホウ酸90重量部とホウ砂10重量部を混合して木
材防虫剤を得た。
比較例 ３
８ホウ酸ナトリウム４水和物からなる木材防虫
剤を得た。
試験例 １
着色防止効果確認（室内試験）
第１表に示す各例の薬剤を各々水に２重量％溶
解して得た水溶液を着色しやすい南洋材（2.5cm
×10cm×20cm）に減圧注入（150〜200／m3）
し、３日間室内風乾後、４日間日光曝露を行い着
色度を見た。その結果は第１表に示す如くであつ
た。
INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to an insect repellent for wood, particularly tropical wood. BACKGROUND OF THE INVENTION Recently, a method of injecting an aqueous solution of boron compounds and fluorine compounds into the wood under pressure or under reduced pressure has come to be widely used to prevent insects from tropical wood such as lauan wood. These compounds are recognized as insect repellents by the Japanese Agricultural Standards for lumber, and their insect repellent effects are widely known. As such boron-based agents, mixtures of borax and boric acid or sodium octaborate tetrahydrate are widely used. The reasons for this are that it is highly safe, inexpensive, easy to handle because it is water-soluble, and is not corrosive to pressure treatment equipment. Problems to be Solved by the Invention However, when South Sea wood is pressurized with a mixture of borax and boric acid or sodium octaborate tetrahydrate,
When treated with insect repellent, the transition area between sapwood and heartwood becomes colored red to reddish-purple. It is particularly common in white wood from Sabah. This coloration is more noticeable during drying than immediately after processing, and the degree of coloration increases particularly when exposed to sunlight. For this reason, the commercial value of the lumber after insect repellent treatment is reduced, which has become a problem. It was confirmed that the degree of coloration is stronger when the pH of the treatment solution is alkaline, and it is further accentuated by air and sunlight. At present, no technology has been established to check and select materials to be colored in advance. Therefore, it has become necessary for insect repellents (treatment liquids) to have the ability to prevent coloring. Therefore, the degree of coloring can be reduced by lowering the pH of the processing solution by changing the mixing ratio of borax and boric acid or by adding an acidic component, but it is not perfect and the pH
If the pressure drops to below neutrality, corrosion will occur because the pressurizing device is made of iron. At the same time, iron ions are released into the treatment solution, and these iron ions react with tannin-like substances in the material. Therefore, the treatment liquid becomes dark in color, and the treated material is also finished black. Means for Solving the Problems The following methods can be considered to prevent the coloring of treated materials as described above. (b) Preventing coloring by performing pretreatment. (b) Clean colored materials by performing post-treatment. (c) Adding a coloring inhibitor to the processing solution. (d) Mix a coloring inhibitor with the drug. However, methods (a) and (b) are disadvantageous because they require two steps. Furthermore, method (a) involves surface treatment, which is later subjected to pressure treatment, which makes it ineffective. In method (b), once discolored wood requires fairly strong treatment.
In addition, since not all of one package is colored, it is necessary to untie the bundle. As a result of considering methods (c) and (d) for the following reasons, we found that method (d) is simpler and more economical than method (c), and that it satisfies the following conditions as a color inhibitor. It was found that it was necessary to satisfy the following. (a) It is water soluble. (b) Can be used in combination with boric acid. (c) Do not color the material. (d) High safety and easy handling. (e) It is alkaline and can be used for pH adjustment. (f) Does not cause iron corrosion. (g) Does not affect the determination of boric acid from treated materials. (h) Does not affect the concentration measurement of boric acid in the processing solution. (i) It is inexpensive. Based on the above results, the present inventors researched a wood preventive material that not only has an insect repellent effect but also can prevent the discoloration of treated wood due to insect repellent treatment. It has been discovered that by using these salts in combination, in addition to having an insect repellent effect, it is possible to prevent coloring of treated materials, suppress metal corrosion of processing equipment such as pressurization or depressurization, and reduce staining of processing liquids. That is, an object of the present invention is to provide a wood insect repellent material containing boric acid and phosphoric acid salts as main components. The boric acid used in the present invention is a white crystalline powder that exhibits weak acidity when dissolved in water. In the JAS insect repellent treatment for sawn timber, 0.3% boric acid is added to the sapwood of the treated timber.
It is stipulated that if the above content is present, an insect repellent effect against the Japanese yellow beetle can be obtained. In addition, the phosphoric acid salts used in the present invention include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate,
Examples include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium pyrophosphate, and ammonium salts are particularly preferred. When these phosphoric acid salts are dissolved in water,
Each of them exhibits acidity to alkalinity depending on their properties, but when adjusting the pH of the wood insect repellent of the present invention, it is possible to use them alone or in combination of two or more. The wood insect repellent of the present invention is composed of salts of boric acid and phosphoric acid as described above, and the blending ratio thereof is preferably 70 to 95% by weight of boric acid and 5 to 30% by weight of salt of phosphoric acid. If the amount of boric acid is less than the above-mentioned mixing ratio, there is a concern about the insect repellent effect, and if it is too much, it will affect the various effects of the phosphoric acid salts. In other words, effects such as pH adjustment to near neutrality and metal corrosion prevention are lost. When actually processing the wood insect repellent of the present invention into wood, salts of boric acid and phosphoric acid, and if necessary, other insect repellents, fungicides, etc. are dissolved in water simultaneously or separately, and the mixture is pressurized using a conventional method. (or vacuum) injection process. The present invention will be specifically explained below with reference to Examples and Test Examples, but the present invention is not limited thereto. Example 1 85 parts by weight of boric acid and 15 parts by weight of diammonium hydrogen phosphate
The wood insect repellent of the present invention was obtained by mixing parts by weight. Example 2 90 parts by weight of boric acid and 10 parts by weight of triammonium hydrogen phosphate
The wood insect repellent of the present invention was obtained by mixing parts by weight. Example 3 A wood insect repellent of the present invention was obtained by mixing 85 parts by weight of boric acid and 15 parts by weight of disodium hydrogen phosphate. Comparative Example 1 A wood insect repellent was obtained by mixing 70 parts by weight of boric acid and 30 parts by weight of borax. Comparative Example 2 A wood insect repellent was obtained by mixing 90 parts by weight of boric acid and 10 parts by weight of borax. Comparative Example 3 A wood insect repellent consisting of sodium octaborate tetrahydrate was obtained. Test Example 1 Confirmation of anti-coloration effect (indoor test) An aqueous solution obtained by dissolving 2% by weight of each of the chemicals shown in Table 1 in water was prepared using South Sea wood (2.5 cm
×10cm×20cm) vacuum injection (150~200/ m3 )
After air drying indoors for 3 days, it was exposed to sunlight for 4 days and the degree of coloration was determined. The results were as shown in Table 1.
【表】
試験例 ２
着色防止効果確認（実用処理）
第２表に示す各薬剤で行つた実用処理の結果を
第２表に示す。
処理液は各々1.7重量％．処理材は着色しやす
い南洋材（2.5cm×30cm×300cm）を使用。処理方
法は常法通りの加圧注入処理で薬液吸収量は約
150／m3．着色度評価は表１の場合と同じ。[Table] Test Example 2 Confirmation of discoloration prevention effect (practical treatment) Table 2 shows the results of practical treatment performed with each agent shown in Table 2. Each treatment liquid was 1.7% by weight. The treated material is South Sea wood (2.5cm x 30cm x 300cm), which is easily colored. The treatment method is the usual pressurized injection process, and the amount of chemical liquid absorbed is approx.
150/ m3 ． The coloring degree evaluation is the same as in Table 1.
【表】
試験例 ３
鉄腐蝕性試験（室内試験）
第３表に示す各薬剤を各々水に２重量％溶解し
て得た水溶液に、着色しやすい南洋材の木粉を約
24時間浸漬し、過して得られた液に磨いた鉄ク
ギを入れ３日後クギ並びに液の変化を観察した。
結果を第３表に示す。[Table] Test Example 3 Iron Corrosion Test (Indoor Test) Approximately 2% by weight of each agent shown in Table 3 was dissolved in water, and approximately 2% of the South Sea wood powder, which is easily colored, was added to an aqueous solution obtained by dissolving 2% by weight of each of the chemicals shown in Table 3 in water.
After soaking for 24 hours, polished iron nails were placed in the resulting solution, and changes in the nails and the solution were observed after 3 days.
The results are shown in Table 3.
【表】
試験例 ４
比較例２の混合物を使つて実用処理を続けたと
ころ、材への赤い着色は認めなかつたが、加圧
釜、薬液混合槽、材搬入用レール、台車等に明ら
かなサビを認め、さらに処理液が暗色化し処理材
が黒くぽく仕上つた。
試験例 ５
実施例１の混合物を1.7％溶解して得た水溶液
を使つて実用処理を行い、その処理材中のホウ酸
含有量について製材JASのホウ素化合物によつて
防虫処理された材のホウ酸の定量方法に基づいて
分析を行つた結果、処理材の辺材部分の表面から
５mmの深さに於て0.98％のホウ酸が検出され、製
材JASの規格値0.3％以上を充分に満足すること
がわかつた。[Table] Test Example 4 When practical treatment was continued using the mixture of Comparative Example 2, no red coloring was observed on the material, but there was obvious rust on the pressure cooker, chemical mixing tank, material loading rail, trolley, etc. In addition, the treatment solution darkened, resulting in a black finish to the treated material. Test Example 5 Practical treatment was carried out using an aqueous solution obtained by dissolving 1.7% of the mixture of Example 1, and the boric acid content of the treated material was evaluated. As a result of analysis based on the acid quantitative method, 0.98% boric acid was detected at a depth of 5 mm from the surface of the sapwood of the treated lumber, fully satisfying the lumber JAS standard value of 0.3% or more. I found out what to do.