Flame-retardant treated wood building material and method for manufacturing the same

Abstract

To provide flame-retardant treated lumber capable of keeping appearance and flame retardancy in a high-humidity environment.SOLUTION: A coating film containing vinyl chloride resin and / or vinylidene chloride resin is formed on a surface of a lumber to which a flame retardant is injected. The coating film containing the vinyl chloride resin and / or vinylidene chloride resin is preferably transparent in a level allowing its grain of the lumber to be recognized. When using a flame-retardant treated lumber outdoors, it is preferably to apply a top coat from the coating film containing the vinyl chloride resin and / or vinylidene chloride resin. The coating film formed with the top coat is preferably transparent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a flame-retardant treated wood building material obtained by injecting a flame retardant into wood, and a method for manufacturing a flame-retardant treated wood building material. [Background technology]

[0002] Among the wood used as interior building materials, flame-retardant treated wood, which has been given flame retardancy by injecting flame retardants, is widely used in areas subject to fire safety restrictions under the Building Standards Act, such as hotels, theaters, exhibition halls, and restaurants.

[0003] One method for injecting flame retardants into wood is the depressurization / pressure injection method, in which dried wood is placed in a pressure vessel, the inside is depressurized to remove the internal air from the wood, the flame retardant is introduced into the pressure vessel, and then injected under pressure into the wood's fibrous structure (for example, Patent Document 1).

[0004] Other examples of flame retardants include ammonium phosphate, guanidine phosphate, and dicyandiamide (see, for example, Patent Document 2).

[0005] When these flame-retardant treated woods are used outdoors, or even indoors in high-temperature and high-humidity environments, the injected flame retardant may redissolve and precipitate on the wood surface (hereinafter referred to as "leaching"), causing the wood surface to turn white, impairing its appearance, and potentially reducing its flame-retardant performance.

[0006] To prevent such leaching, there is a method of applying a two-component flame-retardant polyurethane resin coating, consisting of a base and a hardener, to the surface of flame-retardant treated wood (for example, Patent Document 3).

[0007] However, conventional paints have the drawback of not providing sufficient protection against leaching under high temperature and humidity conditions. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-277209 [Patent Document 2] Japanese Patent Application Publication No. 5-77207 [Patent Document 3] Japanese Patent Publication No. 2005-271309 [Overview of the project] [Problems that the invention aims to solve]

[0009] The problem we aim to solve is that, in high-humidity environments, flame-retardant treated wood, obtained by injecting flame retardants, may have its appearance compromised and its flame retardancy reduced as the injected flame retardant leaches out onto the wood surface. [Means for solving the problem]

[0010] The present invention is a flame-retardant treated wood obtained by injecting a flame retardant into wood, characterized in that a coating film containing polyvinyl chloride resin and / or vinylidene chloride resin is formed on the surface of the wood.

[0011] The present invention is a method for producing flame-retardant treated wood, characterized in that a flame retardant is injected into the wood, and then a coating composition containing polyvinyl chloride resin and / or vinylidene chloride resin is applied to the surface of the wood.

[0012] The present invention relates to a method for producing flame-retardant treated wood for outdoor use, characterized by injecting a flame retardant into the wood, applying a coating composition containing polyvinyl chloride resin and / or vinylidene chloride resin to the surface of the wood, and then applying a urethane coating resin. [Effects of the Invention]

[0013] According to the flame-retardant treated wood of the present invention, the flame retardant injected into the flame-retardant treated wood is less likely to leach out, thus offering the advantages of excellent aesthetic maintenance and less reduction in flame retardancy. [Modes for carrying out the invention]

[0014] Hereinafter, the present invention will be described in detail. In the flame-retardant treated wood of the present invention, a transparent coating film containing a vinyl chloride resin and / or a vinylidene chloride resin is formed on the surface of wood injected with a flame retardant.

[0015] The shape of the wood is not particularly limited. It may be in the shape of a plate with a thickness of 8 mm to 50 mm, or may be prismatic or cylindrical.

[0016] The wood type based on processing form is not particularly limited. Examples thereof include sawn timber, plywood, laminated veneer lumber (LVL), glued laminated timber, cross-laminated timber (CLT), and the like.

[0017] The tree species of the wood is not particularly limited. Examples include coniferous trees such as cedar, cypress, and larch, and broadleaf trees such as oak and chestnut.

[0018] A water-soluble flame retardant is injected into the interior of the wood. Examples of the flame retardant include phosphoric acid compounds such as phosphoric acid, ammonium phosphate, ammonium polyphosphate, and guanidine phosphate; boric acid compounds; sulfuric acid compounds such as ammonium sulfate; halogen compounds; and the like. Among these, guanidine phosphate is preferably used from the viewpoint of suppressing leaching in outdoor environments.

[0019] The method for injecting the flame retardant is not particularly limited; injection by a pressure injection method is generally used, but an aqueous flame retardant solution or an alcoholic flame retardant solution may be applied and allowed to penetrate into the wood surface.

[0020] As an example of the pressure injection method, after dried wood is accommodated in a pressure vessel, the pressure vessel is sealed and the inside thereof is depressurized. Subsequently, while maintaining the reduced pressure state inside the pressure vessel, an aqueous flame retardant solution is supplied into the pressure vessel, and the entire wood is immersed in the aqueous flame retardant solution. Thereafter, compressed air is supplied into the pressure vessel by an air compressor or the like to pressurize the inside of the pressure vessel, and the flame retardant is injected into the wood. Next, the aqueous flame retardant solution is discharged, the wood is taken out, and dried by a dryer to obtain the flame-retardant treated wood.

[0021] The coating film containing the aforementioned vinyl chloride resin and / or vinylidene chloride resin is preferably transparent enough to allow the wood grain to be visible. This configuration provides excellent aesthetic appeal for flame-retardant treated wood.

[0022] The coating film containing the aforementioned vinyl chloride resin and / or vinylidene chloride has a water vapor transmission rate of 1 to 50 g / m² when measured under conditions of 3 μm thickness, 40°C, and 90 RH. 2 It is preferable that the amount be 2-40 g / m² per day. 2 It is more preferable that the amount be less than / day, and 3-10 g / m 2 It is most preferable that the water vapor transmission rate is 1 g / m³ or less per day. 2 If the amount is less than 1 day, the coating may swell due to the evaporation of moisture contained in the wood. Conversely, 50g / m 2 If the duration exceeds one day, the flame retardant may not be sufficiently effective in preventing leaching.

[0023] The coating film containing the vinyl chloride resin and / or vinylidene chloride resin may use either the vinyl chloride resin or the vinylidene chloride resin alone, or in combination. It is more preferable to use the vinylidene chloride resin alone. When used in combination, it is preferable to use 500 parts by mass or more of the vinylidene chloride resin per 100 parts by mass of the vinyl chloride resin.

[0024] Other synthetic resins may be used in combination with the coating film containing the vinyl chloride resin and / or vinylidene chloride resin. Examples include acrylic resin, urethane resin, polyethylene resin, polypropylene resin, vinyl acetate resin, etc. These may be used in combination with the vinyl chloride resin and / or vinylidene chloride resin, or by copolymerization.

[0025] The composition of the paint composition containing the vinyl chloride resin and / or vinylidene chloride resin is, for example, as follows:

[0026] 20 parts by mass of vinylidene chloride resin, 80 parts by mass of 2-butanone as a solvent, 5 parts by mass of silica as a matting agent, 1 part by mass of an antifoaming agent, and 1 part by mass of a dispersant.

[0027] Preferably, the content of the vinyl chloride resin and / or vinylidene chloride resin in the entire paint composition is 3 to 50% by mass.

[0028] Other synthetic resins may be used in combination with the aforementioned paint containing vinyl chloride resin and / or vinylidene chloride resin. Examples include acrylic resin, urethane resin, polyethylene resin, polypropylene resin, vinyl acetate resin, etc. These may be mixed with vinyl chloride resin and / or vinylidene chloride resin, or used in copolymer form.

[0029] The paint containing the vinyl chloride resin and / or vinylidene chloride resin may use either the vinyl chloride resin or the vinylidene chloride resin alone, or in combination. It is more preferable to use the vinylidene chloride resin alone. When used in combination, it is preferable to use 500 parts by mass or more of the vinylidene chloride resin per 100 parts by mass of the vinyl chloride resin.

[0030] The aforementioned solvent is not limited to 2-butanone, but can be any solvent capable of dissolving vinyl chloride resin and / or vinylidene chloride resin. Examples include toluene, xylene, tetrahydrofuran, ethyl acetate, and butyl acetate. Mixtures of these may also be used. Of these, ethyl acetate is preferred due to its volatility and odor.

[0031] The vinyl chloride resin and / or vinylidene chloride resin may be dispersed in water using a surfactant or the like, without being dissolved in a solvent. This configuration makes it possible to reduce the odor of the paint composition containing the vinyl chloride resin and / or vinylidene chloride resin, so that it can be applied to existing flame-retardant treated wood in buildings without isolating residents or building users.

[0032] The amount of the coating composition containing the vinyl chloride resin and / or vinylidene chloride resin applied is 5 to 100 g / m² of vinyl chloride resin and / or vinylidene chloride resin.2 preferably 10 to 50 g / m 2 , and more preferably 2 less than 5 g / m 2 , there is a risk that a sufficient leaching prevention effect cannot be obtained, and when it exceeds 100 g / m

[0033] The coating film thickness of the coating composition containing the vinyl chloride resin and / or vinylidene chloride resin is preferably 2 to 80 μm, more preferably 10 to 50 μm. When the thickness is less than 2 μm, there is a risk that a sufficient leaching prevention effect cannot be obtained, and when the thickness exceeds 80 μm, there is a risk that the calorific value generated during a fire increases.

[0034] If necessary, the coating composition containing the vinyl chloride resin and / or vinylidene chloride resin is not limited to antifoaming agents and dispersants, and additives used in ordinary coating compositions can be used. Examples thereof include wetting agents, surface conditioners, thickeners, pH adjusters, ultraviolet absorbers, light stabilizers, preservatives, antioxidants, and the like.

[0035] The coating composition containing the vinyl chloride resin and / or vinylidene chloride resin may contain coloring pigments or extender pigments. Examples include coloring pigments such as titanium oxide, carbon black, and iron oxide, and extender pigments such as calcium carbonate, talc, mica, and barium sulfate. These can be used within a range that does not impair the transparency of the coating film containing the vinylidene chloride resin.

[0036] The matting agent is not limited to silica, and any matting agent used in ordinary coating compositions can be optionally used. Examples thereof include spherical acrylic resins and the like. Furthermore, a glossy paint may be provided without using a matting agent.

[0037] The coating composition containing the vinyl chloride resin and / or vinylidene chloride resin is applied to the surface of wood that is assumed to be exposed to the combustion heat of fire when flame-retardant treated wood is used as a part of a building. Of course, the coating composition may also be applied to surfaces that are not exposed to the combustion heat of fire.

[0038] The paint composition containing the aforementioned vinyl chloride resin and / or vinylidene chloride resin is preferably applied to at least the surface of the flame-retardant treated wood that is exposed to the heat of combustion during a fire.

[0039] The coating composition containing the aforementioned vinyl chloride resin and / or vinylidene chloride resin can be applied to flame-retardant treated wood using the same methods as for ordinary paints. Examples include brush, spray, and roller application. Alternatively, it may be applied by dipping, or by using coating machinery such as a curtain flow coater or roll coater.

[0040] The timing for applying the paint composition containing the vinyl chloride resin and / or vinylidene chloride resin to the flame-retardant treated wood may be immediately after injecting the flame retardant into the wood and letting it dry, or it may be applied after the flame-retardant treated wood has been installed in an existing building.

[0041] When using flame-retardant treated wood outdoors, it is preferable to apply a topcoat paint over the coating containing the aforementioned polyvinyl chloride resin and / or vinylidene chloride resin. As the topcoat paint, acrylic resin paint or urethane resin paint is preferred, and a urethane resin paint combining polycarbonate diol and hexamethylene diisocyanate is more preferable. This configuration provides superior waterproofing, thereby improving the leaching prevention effect.

[0042] The aforementioned urethane resin coating is preferably a two-component mixture. When applying the aforementioned urethane resin coating, it is preferable to apply it to areas where a coating containing vinyl chloride resin and / or vinylidene chloride resin has not been formed. This configuration allows the entire flame-retardant treated wood to be waterproofed, thereby further improving the leaching prevention effect.

[0043] The coating film formed by the aforementioned urethane resin paint is preferably transparent. This configuration provides excellent aesthetic appeal for flame-retardant treated wood.

[0044] The coating film formed by the aforementioned urethane resin paint is preferably 50 to 200 μm thick, and more preferably 100 to 150 μm thick. This configuration provides excellent waterproofing, further improving the leaching prevention effect. If the coating film thickness is less than 50 μm, the waterproofing effect will not be sufficient, and conversely, if it exceeds 200 μm, the workability of the application may decrease.

[0045] The aforementioned urethane resin coating can be used with additives commonly used in paints. Examples include defoaming agents, dispersion agents, wetting agents, surface modifiers, thickeners, pH adjusters, UV absorbers, light stabilizers, and preservatives.

[0046] The aforementioned urethane resin coating may contain coloring pigments and extender pigments. Examples include coloring pigments such as titanium dioxide, carbon black, and iron oxide, and extender pigments such as calcium carbonate, talc, mica, and barium sulfate. These can be used insofar as they do not impair the transparency of the coating film formed by the urethane resin coating.

[0047] The aforementioned urethane resin paint may be used as either a matte or glossy paint.

[0048] The effects of the present invention will be explained below with reference to examples and comparative examples. First, a flame retardant aqueous solution was prepared by mixing 25 parts by mass of ammonium phosphate and 5 parts by mass of boric acid in 100 parts by mass of water. A piece of cedar lumber measuring 12 mm thick x 99 mm wide x 99 mm long was submerged in this flame retardant aqueous solution, and weights were placed on top to prevent the lumber from floating. The solution was then placed in a pressure vessel, and the pressure was reduced to maintain a vacuum for 60 minutes. Subsequently, the pressure was increased (4 kgf / cm2) and held for 50 minutes, after which the pressure was reduced to atmospheric pressure. After that, the cedar lumber was removed from the flame retardant aqueous solution and dried by hot air drying (temperature 65°C) for 7 days to obtain the test specimen substrate. The amount of flame retardant fixed at this time was approximately 150 kg / m 3 The surface of this substrate was coated with paints A to E shown in Table 1 and dried to create a test specimen.

[0049] The high humidity exposure test was conducted by placing the test specimens in a constant temperature chamber at 35°C × 90RH% (simulating a room without air conditioning during summer rainfall) for 7 days, and then leaving them in a room at 23°C × 50RH% for 1 day, after which the appearance of the test specimen surface was observed. The evaluation was as follows: ◎ for no change in appearance, ○ for slight change, △ for cloudy but with visible wood grain, and × for leaching (precipitation of crystals).

[0050] The flammability test was performed using the cone calorimeter method specified in ISO 5660-1, with test specimens that had undergone the appearance change test. The evaluation was based on a total calorific value of 7.2 MJ / m³ after heating for 10 minutes. 2 The following items are marked with a circle (○): 7.2 MJ / m 2 Exceeding 8 MJ / m 2 The following are △, 8MJ / m 2 Anything exceeding the limit was marked with an "X". The test results are shown in Table 2.

[0051] The outdoor weather resistance test involved immersing a 70mm wide x 150mm long x 12mm thick cedar lumber in a 20% by mass guanidine phosphate aqueous solution for 7 days, then drying it in a 50°C drying room for 2 weeks. Finally, paint A shown in Table 1 was applied at a rate of 70g / m². 2 The surface was then coated and allowed to dry. Subsequently, the topcoat paint shown in Table 3 was applied to the surface at a rate of 80 g / m². 2 The sample was coated and dried to prepare the test specimen. The test was conducted according to JIS K5600-7-7 General test methods for paints - Part 7: Long-term durability of paint films - Section 7: Accelerated weathering and accelerated lightfastness (xenon lamp method), using a light emission intensity of 60 W / m² with wavelengths of 300 nm to 400 nm. 2 The test was conducted for 300 hours at a black panel temperature of 63°C and a test specimen wetting cycle of A. The evaluation criteria were as follows: ◎ for almost no change in appearance, ○ for slight discoloration, △ for crystal precipitation between the wood and the coating, and × for white crystal precipitation on the surface of the test specimen. The test results are shown in Table 3.

[0052] In addition, among the topcoat paints in Table 3, the urethane resin paint used is a urethane resin paint made from a combination of polycarbonate diol and hexamethylene diisocyanate (product name: Suncracy MSY-323, manufactured by Sansho Co., Ltd.).

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

Claims

1. Flame-retardant treated wood obtained by injecting a water-soluble flame retardant into wood, A transparent coating made of polyvinyl chloride resin and vinylidene chloride resin, with a coating thickness of 2 to 80 μm, is applied to the surface of the wood. Or, A transparent coating film containing the aforementioned vinyl chloride resin and vinylidene chloride resin, and one or more synthetic resins selected from acrylic resin, urethane resin, polyethylene resin, polypropylene resin, and vinyl acetate resin. A flame-retardant treated wood that has formed, The transparent coating contains 500 parts by mass or more of vinylidene chloride resin per 100 parts by mass of vinyl chloride resin. Flame-retardant treated wood characterized by [specific feature].

2. After injecting a water-soluble flame retardant into wood, a coating composition consisting of vinyl chloride resin and / or vinylidene chloride resin or A paint composition containing the vinyl chloride resin and / or vinylidene chloride resin and one or more synthetic resins selected from acrylic resin, urethane resin, polyethylene resin, polypropylene resin, and vinyl acetate resin. A method for producing flame-retardant treated wood for outdoor use, characterized by applying a certain material and then applying a two-component transparent urethane resin paint to a film thickness of 50 to 200 μm.

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