JPH09300312A - Manufacture of modified wood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the elution of a metal oxide by the action of water from occurring and enable flame retarding performance to be displayed stably over a long period of time by impregnating wood with methylsiloxane oligomer containing phosphorus and/or boron and curing the oligomer as shown by spe cific formula. SOLUTION: Wood is impregnated with a methylsiloxane oligomer solution shown by formula: [CH3 SiO1.5 ]x [(CH3 )a SiO(4-a)/2 ]y [MO1.5 ]z containing phosphorus and/or boron comprising a hydroxyl and/or a 1-4C alkoxy group as the terminal. Next, the wood is hydrolyzed or thermally decomposed, and further, is polycondensated and cured. In addition, the wood is made water-repellent by forming methyl silicone resin containing a noninflammable phosphorus oxide and/boron oxide in the cellular wall and thus a modified wood which is noninflammable semipermanently is obtained. In formula, M is the selected one or at least, two types of P, PO or B; (x), (y), (z) are positive numbers, the average ratio of (x+y):(z) is within the range of 99:1-50:50; and (a) is an integer of 2 or 3.

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 flame-retarded wood, and in particular, it prevents metal oxides formed in wood from being eluted by the action of water, thereby making the wood flame-retardant. The present invention relates to a method for producing modified wood which is semi-permanently applied.

[0002]

2. Description of the Related Art When wood is used, its characteristics such as "burning", "rotting", and "inconsistent dimensions" are drawbacks, and its use is limited. Often. In particular, Heisei 2
The Building Standards Law was amended in June 2012 to allow wood to be used in the openings, but it is necessary to clear the flame penetration and flame barrier standard of 60 minutes for A and 20 minutes for Otsu. It is difficult to exceed this standard even if used as it is.

The inventors of the present invention have made earnest studies on the development of wood that has improved these drawbacks. As a result, the wood is impregnated with silicon alkoxide, and silicon oxide is produced and fixed in the wood cell voids by hydrolysis and polycondensation. As a result, a modified wood having excellent flame retardancy, decay resistance, and dimensional stability was found [Journal of the Wood Research Society of Japan 38 (11), 1043 (199).
2)]. This production method is based on the sol-gel method of metal alkoxide, and in the starting solution of metal alkoxide-water-alcohol-catalyst, the metal alkoxide becomes a sol of metal oxide by hydrolysis and self-polycondensation. The solution is further reacted to form a gel. By carrying out this reaction in the wood cells, the inorganic composite with the metal oxide of wood is realized.

However, the process of complexing wood and metal oxides depends largely on the hydrolysis rate of the metal alkoxide used, and the recent intracellular distribution of the metal oxides in wood varies greatly depending on the preparation conditions. Has become clear. For example, in the mineralization of wood using a silicon alkoxide with a low hydrolysis rate, when the wood used is a humidity control specimen (all water contained in the wood is bound water and exists only in the cell wall), The hydrolysis / polycondensation reaction of the silicon alkoxide proceeds only in the cell wall where the bound water is present, and an inorganic composite wood having a cell cavity is obtained.
This composite wood retains the light, strong, and heat-insulating properties of wood, and is a modified wood that has dimensional stability, flame retardancy, and decay resistance while maintaining the porous properties of wood. [The Journal of the Wood Science Society of Japan 39 (3), 301 (199)
3)]. However, when the wood used is a saturated water sample (water whose cell lumen as well as cell walls is filled with water),
It was clarified that not only the inside of the cell wall but also the lumen was filled with the metal oxide, which became the inorganic composite wood by the silicon oxide [Journal of the Wood Research Society of Japan 39 (3), 301 (1).
993)].

However, once the metal alkoxide used is changed, a completely different distribution of inorganic composite wood is obtained. For example, when titanium alkoxide, which has a high hydrolysis rate, is used, titanium oxide is produced only in the cell lumen of the humidity control specimen, and oxide is only produced on the outer surface of the saturated water specimen. It has been found that the inside of the test piece cannot be composited with a metal oxide [Japanese Journal of Wood Research 39 (3), 308 (1993)].

[0006] Furthermore, based on these findings, the relationship between the intracellular distribution of metal oxides and the imparted function was investigated. By selectively complexing metal oxides in the cell wall, It has been revealed that various functions can be effectively expressed with the formation of a small amount of metal oxide. Examples of such composites include inorganic composite woods made of metal oxides such as silicon alkoxides, boron alkoxides, and phosphorus alkoxides. The formed metal oxide is easily dissolved in water and is not stable.

The present invention has been made in view of the above circumstances, and provides a method for producing a modified wood which prevents the elution of metal oxides due to the action of water and can stably exhibit flame retardant performance for a long period of time. The purpose is to provide.

[0008]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that wood contains phosphorus and / or boron and contains 2 methyl groups. The above is a methylsiloxane oligomer containing a siloxane unit [(CH ₃ ) _a SiO _{(4-a) / 2} : a = 2 or 3) directly bonded to a silicon atom, specifically, the following average composition formula (1 ) [CH ₃ SiO _{1.5] x [(CH 3) a SiO (4} -a) / 2 ] _y [MO _{1.5] z} (1) (wherein, M 1 species selected P, from PO and B or 2 X or y, z is a positive number, the average ratio of (x + y): z is 99: 1 to 50:50, and the average ratio of x: y is 99: 1 to 50:50. And a is 2 or 3.), and the terminal has a hydroxyl group and / or 1 to 1 carbon atoms.
4 is impregnated with a methylsiloxane oligomer solution containing phosphorus and / or boron, which is an alkoxy group, then hydrolyzed or thermally decomposed, and further polycondensed and cured,
By forming a methylsilicone resin containing non-combustible phosphorous oxide and / or boron oxide in the cell wall, water repellency is imparted, and the phosphorous oxide and / or boron oxide is less likely to be eluted by the action of water, It is possible to obtain a modified wood in which flame retardancy is maintained semi-permanently. In this case, the methyl siloxane oligomer containing a silicon atom to which two or more methyl groups are directly bonded is used for wood treatment work and preservation. It was found that it has suitable stability.

Therefore, the present invention is based on the above average composition formula (1).
There is provided a method for producing modified wood, which comprises impregnating and curing the oligomer represented by.

According to the manufacturing method of the present invention, it can be applied as a member of an opening based on the new Building Standard Law without deteriorating the original texture of wood, and as a building interior material or exterior material. The flame-retardant wood that can be used can be easily and reliably manufactured. In particular, the present invention semi-permanently and effectively imparts poor solubility to wood, and since the wood is treated with the oligomer of the above formula (1), it has high workability and safety, and is a practical wood modifying material. It can provide technology.

The present invention will be described in more detail below. In the method for producing modified wood of the present invention, wood is impregnated with a specific methylsiloxane oligomer and cured.

Here, the raw material wood used in the present invention is not particularly limited, and examples thereof include log logs, lumber products, sliced veneer, plywood, and the like, and the species thereof are not limited.

The methyl siloxane oligomer used in the present invention has the following average compositional formula (1) [CH ₃ SiO _1.5 ] _x [(CH ₃ ) _a SiO _{(4-a) / 2} ] _y [MO _1.5 ] _z ( 1) is shown.

In this formula (1), M represents one or more selected from P, PO and B. x, y, and z are positive numbers (x + y + z = 1). In this case, (x +
y): z is an average molar ratio of 99: 1 to 50:50, and more preferably 95: 5 to 70:30. If the molar ratio of x + y is less than 50 mols, the water repellency of the methyl silicone resin is insufficient and an effective elution preventing effect cannot be obtained.
Further, x: y is an average molar ratio of 99: 1 to 50:50.
It is. When the molar ratio of x is less than 50 mols, the crosslink density of the methyl silicone resin decreases, while when the molar ratio of y is less than 1 mol, the content of methyl groups in the methyl silicone resin is not sufficient, so in any case Is not sufficient, and an effective elution preventing effect cannot be obtained. Further, when the molar ratio of y is less than 1 mol, the hydrolysis reactivity is too high and the workability of wood treatment and the storage stability are deteriorated. In addition, a is 2 or 3.

This methylsiloxane oligomer has a hydroxyl group and / or an alkoxy group having 1 to 4 carbon atoms at the terminal. When the alkoxy group having 5 or more carbon atoms is used, the hydrolysis reaction is too slow and the workability of wood treatment is deteriorated. For example, methoxy, ethoxy, propyloxy and butoxy groups can be used, but industrially advantageous methoxy groups are preferable.

The average degree of polymerization of the methyl siloxane oligomer is preferably from 2 to 50, more preferably from 2 to 20, and the average degree of polymerization is 2.
If it is less than 50, the vapor pressure of the oligomer becomes high, which may cause a safety problem. If it exceeds 50, it takes too long to impregnate the wood.

The methylsiloxane oligomer containing phosphorus and / or boron of the above formula (1) is a methyltrialkoxysilane, dimethyldialkoxysilane, trimethoxyalkoxysilane or a partial hydrolyzate thereof, and phosphoric acid or phosphorous acid. , Trialkyl phosphite, boric acid, trialkyl borate and the like can be obtained by a conventional method of co-hydrolyzing and condensing one or more compounds selected from the following.

In the case of impregnating wood with the above-mentioned methyl siloxane oligomer, the methyl siloxane oligomer may be used as it is for impregnation, or alcohols such as methyl alcohol and ethyl alcohol, and ketones such as acetone and methyl isobutyl ketone. Alternatively, it may be diluted with another solvent and impregnated.

Further, the above-mentioned methyl siloxane oligomer is mixed with other metal oxide precursors such as tetramethoxysilane, tetraethoxysilane, methyl polysilicate and ethyl polysilicate in order to further enhance the flame retardant effect of wood. You may add it. In this case, these precursors may be subjected to cohydrolysis in addition to methyltrialkoxysilane or a partial hydrolyzate thereof when obtaining the above-mentioned methylsiloxane oligomer. Further, in order to impart more water repellency, long-chain alkyltrialkoxysilane, perfluoroalkyltrialkoxysilane, etc. may be cohydrolyzed or mixed and added as described above.

When the wood is impregnated with the above-mentioned methyl siloxane oligomer, the wood may be either in a humidity-controlled state or in a water-saturated state.
It is preferable to adjust the content to ˜50% by weight, and it is preferable to immerse the wood in the methylsiloxane oligomer or the solution thereof, or to impregnate it by using a reduced pressure or pressure injection method.

Next, the wood impregnated with the above-mentioned methyl siloxane oligomer is in a range where the wood is not thermally decomposed, preferably 5
Dry at 0-110 ° C. In this process, the methyl siloxane oligomer is hydrolyzed and then polycondensed to be converted into a silicone resin or gel containing phosphorus oxide and / or boron oxide. Incidentally, the hydrolysis step is carried out with an acidic catalyst,
A mixed solvent of an alkaline catalyst, a metal organic acid salt, an organic metal compound and the like may be used.

Specifically, wood is impregnated with the above-mentioned methyl siloxane oligomer, and at room temperature for about 1 to 7 days for about 10 to 15 days.
It is preferable to hold under a reduced pressure of mmHg, remove from the liquid, leave at room temperature for about 1 day, and then heat-dry at 50 to 110 ° C. for about half to 2 days.

[0023]

EFFECTS OF THE INVENTION According to the present invention, a safe oligomer can be used to treat wood, it is stable without being eluted into water, and it is stable for a long period of time even when exposed to rainwater or condensation. It is possible to obtain a modified wood that maintains the flame retardant effect, impart water repellency to the wood, and have excellent decay resistance and dimensional stability. Moreover, by carrying out the method for producing modified wood according to the present invention, a flame-retarded wood that can be used as a member of an opening that complies with the New Building Standard Law, or as a building interior material or exterior material is obtained. It has features such as mass production.

[0024]

EXAMPLES Next, the contents of the present invention will be explained in detail with reference to examples and comparative examples, but the present invention is not limited to the examples shown below.

Example 1 Methyltrimethoxysilane 6
1.2 g (0.456 mol), dimethyldimethoxysilane 54.0 g (0.45 mol), boric acid 3.1 g (0.
(05 mol) was placed in a 1 liter flask, and 13.7 g of a 30% phosphorous acid aqueous solution (0.05 mol as phosphorous acid) was added dropwise at 30 ° C. with stirring to react. 60 ° C
After aging for 1 hour, a 70% methanol solution of the oligomer was obtained. The initial viscosity of this solution is 2 cSt, and the temperature is 40 ° C. under closed condition.
Even after being stored for 3 months, the viscosity hardly increased. Methanol was further added to this solution to dilute it, and a 10% methanol solution of the oligomer was prepared and used for the experiment. The average composition formula of this oligomer is [CH ₃ SiO _1.5 ] _0.45 [(CH ₃ ) ₂ SiO] _0.45 [P
O _1.5 ] _0.05 [BO _1.5 ] _0.05 , the average degree of polymerization was 6, and the terminals were methoxy groups and hydroxyl groups.

Then, with acetone and water, respectively, 24
Time soxhlet extracted hemlock sapwood (50 mm x 1
A veneer having a size of 00 mm and a thickness of 1 mm) was used as a test piece.
The water content of this test piece was 25%. A test piece of Bettsuga was soaked in a methanol solution of the above oligomer at room temperature and was soaked under a reduced pressure of 150 mmHg for 3 days. Then, the test piece was heat-treated at 65 ° C. for 24 hours and at 105 ° C. for 24 hours to age the gel in the test piece to obtain a modified wood. Weight gain rate (WPG) due to silicone resin containing phosphorus and boron oxide in this modified wood
Was 13.3%. Next, 250 ml of distilled water was put into a 300 ml beaker, stirred at 160 ± 3 rpm, the modified wood test piece prepared was put therein and stirred for 4 hours, and the weight change was examined. 3% of the resin was eluted. As a result of measurement using a thermogravimetric measuring device using this test piece, the residual weight after flaming combustion was 65.8%, but with another test piece not subjected to the elution test, it was 66.0%. there were. The residual weight of untreated wood under the same conditions was 27%.

The physical properties of the modified wood were measured by the following methods. (1) Weight increase rate (WPG) The absolute dry weight (Wu) of an untreated test piece subjected to Soxhlet extraction for 24 hours with acetone and water is determined. Next, after this test piece was made into an inorganic composite, it was placed at 105 ° C. for 24 hours.
After drying for an hour, determine the absolute dry weight (Wt) of the modified wood,
The weight gain rate (WPG) of the modified wood is calculated from the following formula. WPG (%) = [(Wt-Wu) / Wu] × 100
(%) (2) Elution rate of silicone resin (%) 250 ml of deionized water (water temperature 20 to 24 ° C.) is put into a 300 ml beaker and stirred (160 ± 3 times / minute) with a magnetic stirrer. The modified wood test piece is put therein, and after stirring for 4 hours, the dried test piece is taken out and the absolute dry weight (Wt ′) after drying is determined. Letting the weight increase rate of the modified wood after 4 hours from the dissolution test be (WPG '), the dissolution rate of the silicone resin can be calculated from the following formula. Dissolution rate (%) = [(WPG-WPG ') / WPG] x 1
00 (%) (3) Residual rate (%) by thermogravimetric measurement A thermogravimetric measuring device is used to obtain a TG curve of the weight change of the modified wood during the temperature rising process. Here, the weight at 170 ° C is 100
%, And the weight change is shown. For example, in untreated wood, flammable combustion corresponds to a rapid weight loss around 350 ° C, and surface combustion occurs in the region of 370 to 550 ° C. The residual rate (%) by thermogravimetry is calculated corresponding to that at the end of flaming combustion.

Example 2 Methyltrimethoxysilane 1
21.04 g (0.89 mol), trimethylmethoxysilane 1.04 g (0.01 mol), boric acid 3.1 g
(0.05 mol) in a 1 liter flask, 30%
13.6 g of a phosphorous acid aqueous solution (0.05 mol as phosphorous acid) was added dropwise at 30 ° C. with stirring to react.
Aging at 60 ° C. for 1 hour gave a 70% methanol solution of the oligomer. The initial viscosity of this solution was 2 cSt, and there was almost no increase in viscosity even when stored at 40 ° C. for 3 months in a sealed state. Methanol was added to this solution to dilute it, and
A 0% methanol solution was prepared and used for the experiment. The average composition formula of this oligomer is [CH ₃ SiO _1.5 ] _0.89 [(CH ₃ ) ₃ SiO _0.5 ] _0.01
[PO _1.5 ] _0.05 [BO _1.5 ] _0.05 , the average degree of polymerization was 6, and the terminals were methoxy groups and hydroxyl groups.

Next, using this oligomer solution, modified wood was obtained in the same manner as in Example 1. The weight gain (WPG) of this product was 11.1%. In the dissolution test, 6% of the silicone resin was dissolved. In the thermogravimetric test, the residual weight after flaming and burning after the elution test was 65.5%.
However, it was 6 for another test piece that had not been subjected to a dissolution test.
6.0%.

Example 3 Methyltrimethoxysilane 8
1.6 g (0.60 mol), dimethyldimethoxysilane
36.0 g (0.30 mol), trimethyl borate 10.
Take 4 g (0.1 mol) in a 1 liter flask and add water 1
5 g was added dropwise with stirring at 30 ° C. and reacted.
Aged at 60 ℃ for 1 hour, oligomer 65% methanol
A solution was obtained. The initial viscosity of this solution is 2 cSt, and it is sealed.
Even when stored at 40 ° C. for 3 months, the viscosity was hardly increased. this
The solution was diluted by adding more methanol to give 1 of oligomer.
A 0% methanol solution was prepared and used for the experiment. This ori
The average composition formula of Gomer is [CH_ThreeSiO_1.5]_0.60[(C
H_Three)_TwoSiO ]_0.30[BO_1.5]_0.10And the average polymerization
The degree was 6, and the terminals were methoxy groups and hydroxyl groups.

Next, using this oligomer solution, modified wood was obtained in the same manner as in Example 1. The weight gain (WPG) of this product was 11.0%. In the dissolution test, 3.5% of the silicone resin was dissolved. In the thermogravimetric test, the residual weight after flaming combustion after the dissolution test was 63.
It was 9%, but it was 64.0% in another test piece not subjected to the dissolution test.

Example 4 Methyltrimethoxysilane 6
8.0 g (0.50 mol), dimethyldimethoxysilane
30.0 g (0.25 mol), trimethyl phosphite 3
Transfer 1.0 g (0.25 mol) to a 1 liter flask.
Then, 15g of water is added dropwise to the mixture at 30 ° C with stirring to react.
I let it. Aged at 60 ° C for 1 hour to give 60% oligomer content.
A tanol solution was obtained. The initial viscosity of this solution is 2 cSt
Then, even if it was stored at 40 ° C for 3 months in an airtight condition, it did not almost thicken.
Was. Methanol is added to this solution to dilute it and
A 10% methanol solution of Gomer was prepared and used for the experiment.
Was. The average composition formula of this oligomer is [CH_ThreeSiO_1.5]_0.50[(CH_Three)_TwoSiO ]_0.25[P
O_1.5]_0.25 And the average degree of polymerization is 6, and the terminals are methoxy groups and hydroxyl groups.
there were.

Next, using this oligomer solution, modified wood was obtained in the same manner as in Example 1. The weight gain (WPG) of this product was 11.3%. In the dissolution test, 5% of the silicone resin was dissolved. In the thermogravimetric test, the residual weight after flaming and burning after the dissolution test was 64.5%.
However, it was 6 for another test piece that had not been subjected to a dissolution test.
It was 5.0%.

[Comparative Example 1] A soybean sapwood (50 m) which was subjected to Soxhlet extraction for 24 hours with acetone and water, respectively.
A test piece having a water content of 25% obtained by conditioning a single plate (m × 100 mm, thickness: 1 mm) has a reaction solution of trimethyl phosphite, ethanol and acetic acid (molar ratio 1: 1: 0.0).
1) was impregnated under reduced pressure for 3 days at room temperature. Then, the test piece was heat-treated at 65 ° C. for 24 hours and at 105 ° C. for 24 hours to age the gel to obtain an inorganic composite wood. The weight increase rate of this composite wood due to the metal oxide was 9.4%. Next, 250 ml of distilled water was put into a 300 ml beaker, stirred at 160 ± 3 rpm, the prepared test piece was put therein, and the mixture was stirred for 4 hours, and the weight change was examined. % Eluted. As a result of thermogravimetric measurement using a thermogravimetric measuring device using this test piece,
The residual weight after flaming and combustion was 55%, but 67% for the other test pieces that had not been subjected to the dissolution test.

Claims (1)

[Claims] 1. The following average composition formula (1) [CH ₃ SiO _1.5 ] _x [(CH ₃ ) _a SiO _{(4-a) / 2} ] _y [MO _1.5 ] _z (1) (wherein M Represents one or more selected from P, PO and B, x, y and z are positive numbers, and the average ratio of (x + y): z is 99: 1 to 50:50, x: y The average ratio is in the range of 99: 1 to 50:50, and a is 2 or 3.), and the terminal has a hydroxyl group and / or 1 to 1 carbon atoms.
4. A method for producing modified wood, which comprises impregnating and curing a methylsiloxane oligomer containing phosphorus and / or boron, which is the alkoxy group of 4.