JPH01154701A - Improved woody material and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a modified wooden material excellent in durability such as heat resistance, water resistance, hot water resistance, weatherability and dimension stabilizing effect, having a wooden feeling and excellent in productivity by dispersing an impregnation soln. based on a block (poly)isocyanate compsn. in wood to cure the impregnated wood. CONSTITUTION: A modified wooden material is obtained by dispersing an impregnation soln. based on a block (poly) isocyanate compsn. in wood to cure the impregnated wood and a block agent of the block (poly)isocyanate compsn. is dissociated in wood by proper heat treatment and crosslinked with a hydroxyl group of a wood structure (a hydroxyl group of cellulose) by the activation of an isocyanate group rich in reactivity to be cured. Further, when a reactive group (-NH2 , -OH or the like) having active hydrogen is contained in a molecular structure of polyisocyanate, a cured matter having a three-dimensional reticulated structure is formed by self-crosslinking reaction between molecules by a regenerated isocyanate group or the crosslinking with a wood structure and, since the wall polymer films strongly bonded to cell walls of wood appear, physical properties (durability, dimensional stability or the like) is drastically enhanced.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for obtaining a wood-plastic composite.
PC (Wood Plastic Combina)
tion or Wood Plastic Compo
(abbreviation for site)) relates to a modified wood material using processing and a method for producing the same.

[Background technology]

Traditionally, wood materials have been impregnated with polymeric resin liquids such as styrene, methyl methacrylate, vinyl acetate, acrylonitrile, and other vinyl monomers, as well as unsaturated polyesters and acrylic oligomers, either alone or in combination. The wood-plastic composite obtained by polymerization and curing in the wood has superior abrasion resistance, water resistance, strength, dimensional stability, etc. compared to ordinary wood, so it can be used in various ways, either alone or in combination with other materials. It is used for various purposes.

Methods for polymerization and curing include radiation polymerization and catalytic polymerization, but usually a polymerizable resin liquid and a polymerization initiator are mixed, impregnated into wood by injection operation methods such as reduced pressure or pressurization, and then heated. The mainstream is a catalytic polymerization method that involves polymerization and curing.

Since wood is a porous material, when wood is impregnated with a polymeric resin liquid, most of the voids are replaced by this polymeric resin liquid, so the resulting wood-Plus Deck composite usually contains 120% or more of resin. The impregnation rate is (weight of polymerized and cured resin/weight of wood x 100%). Because such a large amount of polymeric resin liquid is required, the cost is high, and the resulting wood
The surface of plastic composites has a strong plastic feel, and the original wood texture (wood skin, warmth, soft taste, texture) of wood materials has disappeared. Furthermore, in the case of a high batting rate, when the polymerizable resin is cured by heating in wood, voids are created between the injected cured resin (polymer) and the wood structure due to curing shrinkage during polymerization. For this reason, water enters into the voids, causing the area to appear white (whitening), and there is also the problem that water resistance such as dimensional stability is not improved much.

Furthermore, heating polymerization curing requires a uniform heating operation for a certain period of time, and complete curing will not occur unless certain conditions such as the type of material, thickness, and amount of polymerization initiator are maintained. At this time, if unreacted polymerizable monomer remains, various problems may occur, such as the odor of the unreacted monomer remaining in the wood-plastic composite or the unreacted sludge leaching out. Furthermore, commonly used verdiyl peroxide,
A mixed system of a polymerizable initiator such as cumene hydroperoxide or azobisisobutyrolnitrile with a polymerizable resin has a short pot life, and problems such as gelation may occur, especially during high temperature periods such as summer.

Research has been carried out to improve these shortcomings of wood-plastic composites, and recently a method has been used to reduce processing costs by diluting monomers or acrylic functional oligomers in an appropriate solvent and then injecting them into the wood. ing. However, it takes a long time for polymerization and curing, uneven polymerization occurs, and deformation and cracking of the wood occur due to curing and shrinkage, so this does not result in a significant improvement.

Furthermore, a method is also used in which a solvent-soluble polymer is diluted with a solvent and then injected into the material and the solvent is volatilized. In this case, the polymer simply fills the cell lumen of the wood and has a chemical bond with the wall or a strong interaction with it (
Since there is no interaction (interaction), almost no improvement in dimensional stability or mechanical performance can be expected.

[Purpose of the invention]

The purpose of this invention is to create a modified wood that has excellent durability such as heat resistance, water resistance, hot water resistance, and weather resistance, as well as dimensional stability effects, has a wood feel (finishing, texture), and has excellent productivity. An object of the present invention is to provide a material and a method for producing the same.

[Disclosure of the invention]

The modified wood material of the present invention is obtained by dispersing and curing an impregnating liquid containing a block (poly)isocyanate composition as a main component in wood.

That is, according to the present invention, the blocking agent of the block (poly)isocyanate composition is dissociated by moderate heat treatment in the wood, and the highly reactive isocyanate groups are activated to interact with the hydroxyl groups of the wood tissue (cellulose hydroxyl groups). Cures by crosslinking. Furthermore, if the molecular structure of the polyisocyanate contains a reactive group with activated hydrogen (-NH, -OH, etc.), the regenerated isocyanate group will cause a self-crosslinking reaction between molecules or crosslinking with wood tissue. It becomes a cured product with a three-dimensional network structure, and a wall polymer film that is firmly connected to the cell walls of the wood appears, so physical properties (durability, dimensional stability, etc.) can be dramatically improved.

In addition, the modified wood material of the present invention includes a step of dissolving a block (poly)isocyanate composition in an organic solvent to create an impregnation solution, a step of impregnating wood with the impregnation solution, and a step of making an organic material from the impregnated impregnation solution. It includes a step of crosslinking and curing the (poly)isocyanate composition by volatilizing the solvent.

According to this invention, the block (poly)isocyanate composition is dissolved in an organic solvent to create an impregnating liquid and the wood is impregnated with this. The impregnating property and permeability of the impregnating liquid inside the wood are increased, which is more effective in improving the performance of the wood.

Block (poly) isocyanate compositions include aromatic isocyanates such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and 1,5-naphthalene diisocyanate (NDI), or hexamethylene diisocyanate ( HD
r), aliphatic isocyanates such as xylene diisocyanate (XDI) and hydrogenated MDI (HMDr), and furthermore, these diisocyanate compounds and polyethylene adipate (PEA), polypropylene adipate (PPA), polybutylene adipate (PBA), and polyethylene. Polyester polyols such as (PEPA) or polyethylene glycol (PEG)
), polyether polyols such as polypropylene glycol (PPG), polyethylene propylene glycol (PEPG), and polytetramethylene glycol (PTMG), or reaction compositions with hydroxyl compounds such as acrylic polyols and polybutadiene polyols (terminal NGO urethane Prepolymer) terminal isocyanate 7% (NCOM) methanol, ethanol, phenol, ethyl mercaptan, β-thionaphthol 1
．． A composition whose structure is masked with a blocking agent such as N-methylaniline, acetoxime, microhexanone oxime, acetylacetone, or ethyl acetoacetate, and the blocking agent is dissociated by heat treatment such as heating, and the active isocyanate group is regenerated.

The average molecular weight of the block (poly)isocyanate composition used in this invention is desirably not more than so, ooo from the viewpoint of impregnating into wood materials or improving physical properties.

As the organic solvent for dissolving these block (poly)isocyanate-based compositions alone or in combination, it is necessary to use those that have good compatibility and affinity for the wood structure, such as methanol, n-butyl alcohol, etc. Examples include alcohols such as ethyl acetate and n-butyl acetate, ethers such as isopropyl ether, tetrahydrofuran and dioxane, hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. These organic solvents are
Used alone or as a mixed solvent of two or more. The concentration of the block (poly)isocyanate composition in the organic solvent can be appropriately determined based on the impregnating property of the resin, impregnation rate, work rate, etc., and is not particularly limited, but usually at a temperature of 50% or less. It is desirable to set it to .

Furthermore, in some cases, a curing accelerator such as dibutyltin dilaurate may be added to this impregnating liquid composition.

Wooden materials impregnated with impregnating liquid have been widely used as building materials for houses and the like. Coniferous trees such as pine, cedar, cypress, toga, oak, oak, beech, ash, shioji, etc.
Examples include solid hardwood such as zelkova, plywood, and laminated wood.

As the impregnation method, in addition to the normal pressure immersion method in which the wood is immersed in the impregnating solution under normal pressure, the reduced pressure normal pressure method or the reduced pressure pressure method in which the wood is immersed under reduced pressure and then immersed under normal pressure or increased pressure can be adopted. Yes, it is determined appropriately depending on the amount of impregnation and the type of wood.

The amount of impregnated block (poly)isocyanate composition is
It can be determined as appropriate within a range that enhances durability such as heat resistance, water resistance, hot water resistance, and weather resistance, and dimensional stability, and does not impair the wood's original finish and texture.

According to the results of research conducted by the present inventors, if the resin impregnation rate is 100% when the voids in the wood are completely filled with resin,
If the resin impregnation rate is in the range of 2 to 80%, preferably 20 to 80%, a modified wood material with a high wood feel tends to be obtained; if it exceeds 80%, the wood feel becomes poor, and if it is less than 2%. In this case, the effect of modifying the wood is small.

After impregnation, the impregnated wood is dried to volatilize the solvent, and the resin is cured by heating or the like. In addition to air drying, forced drying using warm air or hot air, and vacuum drying under reduced pressure can be used to volatilize the solvent.
It is desirable to carry out the process gradually so that the main component does not volatilize or elute together with the solvent.

The curing temperature is basically determined by the activation temperature of the block isocyanate used, but it is usually desirable to set the curing temperature to 100''C or less in order to avoid problems such as deformation and cracking of the wood material itself.

The modified wood material obtained in this way has high heat resistance, because the wood is modified by cross-linking and curing the block (poly)isocyanate composition in the wood to form a strong bond with the wood cells. It has water resistance, hot water resistance, solvent resistance, weather resistance, and high dimensional stability, as well as a woody texture.

In addition, during impregnation treatment, the active isocyanate groups are masked by the block material, so
The pot life is stable, and the influence of moisture in the wood is small, so productivity is improved.

[Effects of the present invention]

According to this invention, high durability and dimensional stability can be imparted to wood while maintaining its original woody feel.

Moreover, it is possible to ensure a high pot life and improve productivity.

Example 1: An impregnating solution was prepared by diluting a polyisocyanate crosslinking agent (M2111 manufactured by Daiichi Kogyo Seiyaku ■) with an acetone solvent to a 15% solution.

On the other hand, rice pine straight grain board (IOX 150X 150 (mm)
, moisture content 14.3%), peripheral straight-grained board (IOX 150X
150 (mm), water content 13.3%) and Japanese cypress straight grain board (10 x 150 x 150 (mm), water content 12.
0%) in each vacuum impregnation pot, and
After exhausting to rr, the impregnating solution was injected to obtain impregnated wood.

This was dried in a hot air dryer at 48°C for 10 hours, and then heated for 4 hours at a temperature of 93°C to obtain each impregnated and cured sample. A S in these 24 hour underwater immersion
E (anti-swelling efficiency)
cy+ anti-swelling ability) was 49.45.53. In addition, the ASE value was calculated|required by the following formula.

vc-Vt vc; volumetric expansion coefficient of untreated material ■t; volumetric expansion coefficient of treated material Example 2: Polyisocyanate crosslinking agent (M2O44 manufactured by Daiichi Kogyo Seiyaku ■) was diluted to a 20% solution with methyl alcohol solvent. Then, 0.5 pHR of a curing accelerator (dibutyltin dilaurate) was added to prepare an impregnating solution.

On the other hand, solid oak board (15X 100X 120 (am
), moisture content 15.0%), solid beech board <15 x 1
00x 120 (am), moisture content 14.2%) and solid zelkova board (15 x 100 After exhausting the air, an impregnating solution was injected to obtain impregnated wood.

This was dried in a hot air dryer at 50°C for 12 hours, and then heated for 3 hours at a temperature of 125°C to obtain impregnated hardened wood. ASE at temperature during 30 hours is 62,65.5
It was 5.

Example 3: A polyisocyanate crosslinking agent (Elastron E37 manufactured by Daiichi Kogyo Seiyaku ■) was diluted to 25% with methyl alcohol solvent, and a catalyst (Elastron Ca manufactured by Daiichi Kogyo Seiyaku ■) was diluted to 25%.
t32) was added at 0.5 pHR to create an impregnating solution.

On the other hand, Japanese pine straight grain board (12X70X 10100 (a, moisture content 12.3%), Japanese cypress board (12X70X 100
100 (moisture content 11.0%) and solid zelkova board (12X
70X 100100 (water content 11.8%) was set in a vacuum impregnation pot, and after the inside of the pot was evacuated to 1 Qtorr, the impregnating liquid was injected to obtain impregnated wood.

This was dried in a hot air dryer at 55°C for 12 hours, and then heated for 1 hour at a temperature of 150°C to obtain each impregnated cured wood. The ASE of these 30 hour immersion in water is 68,6
It was 2.58.

Example 4: A polyisocyanate crosslinking agent (M2120 manufactured by Daiichi Kogyo Seiyaku ■) was added to the impregnating solution of Example 3 to give a 30%
An impregnating liquid was prepared by converting it into a solution.

On the other hand, spider solid wood board (9 x 80 x 150 (ms), moisture content 14.0%) and rice cedar straight grain board (9 x 80 x 150
(m+n), water content 13.0%) were each set in a vacuum impregnation pot, and after evacuating the inside of the pot to 15 torr, the impregnating liquid was injected to obtain impregnated wood.

This was dried in a hot air dryer at 62°C for 10 hours, and then heated for 1.5 hours at a temperature of 150°C to obtain impregnated hardened wood. The ASE for these 40 hours of immersion in water is 60.
．． It was 52.

Claims (3)

[Claims] (1) A modified wood material obtained by dispersing an impregnating liquid containing a block (poly)isocyanate composition as a main component into wood and curing it. (2) The impregnation rate of the impregnating liquid into the wood is in the range of 2 to 80% when the resin impregnation rate when the resin completely fills the voids in the wood is 100%. (1
) The modified wood material described in section 2. (3) A step of dissolving the block (poly)isocyanate composition in an organic solvent to create an impregnating solution, and volatilizing the organic solvent from the impregnating solution to the block (
A method for producing a modified wood material, comprising the step of crosslinking and curing a poly)isocyanate composition.