Water-based paint

Abstract

To provide a water-based paint in which an abnormality in appearance such as agglomeration in the formed coating film and a deterioration in physical property are suppressed, and has improved flame retardancy.SOLUTION: Provided is a water-based paint that contains lignocellulose modified with a flame-retardant compound having a specific structural formula, water as a volatile component, and a synthetic resin as a coating film-forming component. Examples of the flame retardant compound include N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid)tetra(2,4,6-tribromophenyl).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an aqueous paint containing lignocellulose modified with a specific flame-retardant compound, water as a volatile component, and a synthetic resin as a component for forming a coating film. [Background technology]

[0002] As disclosed in the following Patent Document 1, a foaming type water-based paint containing a low molecular weight flame retardant such as ammonium polyphosphate or melamine, and a water-based epoxy resin is known.

[0003] Also known is lignocellulose modified with a flame-retardant compound having a structure described in Chemical Formula 1 of Patent Document 2 below. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-158770 A [Patent Document 2] JP 2020-11924 A Summary of the Invention [Problem to be solved by the invention]

[0005] The paint of Patent Document 1 contains a flame retardant, and therefore is believed to have improved flame retardancy to a certain degree. However, conventional water-based paints to which low molecular weight flame retardants such as those of Patent Document 1 are added have problems with the deterioration of the physical properties of the paint film, such as a decrease in the elastic modulus of the paint film. In addition, depending on the type of flame retardant, when the flame retardant is added to the water-based paint, aggregation may occur in the formed paint film.

[0006] Some of the present inventors developed the flame retardant of Patent Document 2, but the flame retardant was developed for the purpose of adding to solid synthetic resin materials. For this reason, lignocellulose modified with a flame retardant having a specific structure was dried and added to a synthetic resin. Patent Document 2 does not mention the use of the flame retardant in water-based paints.

[0007] An object of the present invention is to provide a water-based coating material which suppresses abnormal appearance such as aggregation in the formed coating film and deterioration of physical properties, and has improved flame retardancy. [Means for solving the problem]

[0008] The above problems are solved by providing a water-based paint that contains lignocellulose modified with a flame-retardant compound having the structure of the following [Chemical Formula 1], water as a volatile component, and a synthetic resin as a component that forms a coating film. [ka] [wherein, two of R1 to R3 are groups shown in [Chemical Formula 2] below, and are the same or different from each other; The remaining one of R1 to R3 is lignocellulose. [ka] [However, R4 and R5 are a group that does not contain a flame-retardant element or an aryl group substituted with a group that contains a flame-retardant element, and may be the same or different.]

[0009] The water-based paint preferably contains 1 to 30% by mass of the lignocellulose modified with the flame-retardant compound. The water-based paint can be such that the light transmittance of a solidified coating film having a thickness of 50 μm is 60% or more at wavelengths of 450 nm, 565 nm, and 625 nm. Effect of the Invention

[0010] According to the present invention, it is possible to provide a water-based coating material which suppresses abnormal appearance such as aggregation in the formed coating film and deterioration of physical properties, and has improved flame retardancy. [Brief description of the drawings]

[0011] [Figure 1] 1 is a graph showing the results of an analysis of the relationship between strain and stress for samples made of the water-based paints of Examples 1 to 3 and Comparative Example 1. [Diagram 2] 1 is a graph showing the results of an analysis of the relationship between strain and stress for samples made of oil-based paints according to Comparative Examples 2 to 4. [Diagram 3] 1 is a graph showing the results of measuring the transmittance of light at each wavelength for samples made of the water-based paints of Examples 1 to 3 and Comparative Example 1. [Figure 4] 1 is a graph showing the relationship between the content of flame-retardant lignocellulose and the transmittance of light having a wavelength of 550 nm. [Diagram 5] 1 is a graph showing the relationship between the total calorific value measured with a cone calorimeter and the elapsed time for each sample made of the water-based paint of Example 1, Example 3, and Comparative Example 1. [Figure 6] 1 is a graph showing the relationship between the total calorific value measured with a cone calorimeter and the elapsed time for each sample made of the oil-based paints of Comparative Examples 2, 3, and 4. [Figure 7] 1 is a graph showing the relationship between the heat generation rate measured with a cone calorimeter and the elapsed time for each sample made of the water-based paint of Example 1, Example 3, and Comparative Example 1. [Figure 8] 1 is a graph showing the relationship between the heat generation rate measured with a cone calorimeter and the elapsed time for each sample made of the oil-based paints of Comparative Examples 2, 3, and 4. [Figure 9] Photographs showing the appearance of coating films made from the paints of Example 3, Comparative Example 1, Comparative Example 3, and Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Preferred embodiments of the water-based paint of the present invention will be described below. The embodiments described below are merely limited examples, and the technical scope of the present invention is not limited to the embodiments described below.

[0013] The water-based paint contains lignocellulose modified with a flame-retardant compound having the structure shown in Chemical Formula 1 below (hereinafter referred to as flame-retardant lignocellulose), water as a volatile component, and a synthetic resin as a component that forms a coating film.

[0014] For example, commercially available water-based paints can be used as the volatile component water and the component forming the coating film synthetic resin. Commercially available water-based paints contain a liquid component containing water and a water-soluble or water-dispersed synthetic resin. Water-dispersed synthetic resins include colloidal dispersion type and emulsion type. Water-soluble and colloidal dispersion types are obtained by adding a neutralizing agent to a synthetic resin synthesized using a hydrophilic solvent. By adding a neutralizing agent, the synthetic resin dissolves or semi-dissolves in water. Emulsion type is produced by emulsion polymerization, and the synthetic resin exists as an emulsion in a liquid component mainly composed of water. Emulsion type also includes those in which a hydrophobic synthetic resin is forcibly emulsified.

[0015] The synthetic resin is not particularly limited, but examples thereof include water-soluble acrylic resin, water-dispersed acrylic resin obtained by emulsion polymerization, forcedly emulsified polyurethane resin, self-emulsified polyurethane resin obtained by directly introducing hydrophilic groups into the molecule, epoxy resin that has been made water-based by modification, fluororesin emulsion, silicone resin emulsion, and copolymers obtained by copolymerizing the monomers that make up these molecules, such as an acrylic-urethane copolymer.

[0016] The water, which is a volatile component, and the synthetic resin, which is a component that forms the coating film, can also be obtained by incorporating the same synthetic resin and water as in the above commercially available water-based paint.

[0017] Flame-retardant lignocellulose can be prepared by synthesizing a flame-retardant compound shown in Chemical Formula 1 below using a known method, and then chemically modifying lignocellulose with the synthesized flame-retardant compound using the known Mannich reaction. [ka] [wherein, two of R1 to R3 are groups shown in [Chemical Formula 2] below, and are the same or different from each other; The remaining one of R1 to R3 is lignocellulose. [ka] [However, R4 and R5 are a group that does not contain a flame-retardant element or an aryl group substituted with a group that contains a flame-retardant element, and may be the same or different.]

[0018] The group containing the flame-retardant element may be any group containing an element that exhibits flame retardancy. Examples of such groups include groups containing a flame-retardant element such as a halogen element such as bromine or chlorine, boron, or silicon. Examples of such groups include a halogen group such as a bromo group or a chloro group, a phosphoric acid group, a nitro group, a nitroso group, an azide group, a boronic acid group, a silyl group such as a trimethylsilyl group, or a hydrocarbon group having a flame-retardant element. Examples of the hydrocarbon group having a flame-retardant element include an alkyl group having 1 to 6 carbon atoms in which hydrogen is substituted with a flame-retardant element.

[0019] The aryl group in the above-mentioned flame-retardant compound may be any group that can be substituted with a group containing a flame-retardant element, and examples of the aryl group include a phenyl group and a naphthyl group.

[0020] Examples of the group not containing a flame retardant element include a hydrogen atom, a cyclohexyl group, an aryl group, and an alkyl group having a carbon number of 1 to 6. The aryl group includes a phenyl group and a naphthyl group.

[0021] R4 and R5 may be the same or different. For example, R4 may be a group that does not contain a flame retardant element, and R5 may be a group that contains a flame retardant element, or vice versa. Specifically, for example, R4 and R5 may both be hydrogen atoms or phenyl groups, or R4 may be a phenyl group and R5 may be a hydrogen atom. R1 and R2 may be the same or different.

[0022] The position at which the upper flame retardant compound is bonded to lignocellulose may be any one of R1 to R3.

[0023] The flame-retardant compound has a plurality of phosphate groups in which hydrogen is replaced by R4 and R5, as shown in [Chemical formula 2]. The phosphate group improves water solubility. The flame-retardant lignocellulose shown in [Chemical formula 1] is water-soluble due to the phosphate group. Since the phosphate group provides hydrophilicity, R4 and R5 can adopt groups having any structure. For example, as described above, if the group contains an element that exhibits flame retardancy, the flame retardancy can be enhanced. In addition, for example, if the group contains an element that exhibits flame retardancy, an environmentally friendly halogen-free paint can be obtained. Even if R4 and R5 do not have a flame-retardant element, the flame-retardant compound exhibits flame retardancy because it contains phosphorus and nitrogen, which are flame-retardant elements.

[0024] Examples of the flame retardant compound include N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid) tetra(2,4,6-tribromophenyl); N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid) tetra(2,6-dibromophenyl); N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid) tetra(4-bromophenyl); N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid) tetraphenyl; and N,N'-(4-amino-1,3,5-triazine-2,6-diyl)bis(phosphoramidic acid).

[0025] In the above example, 2,4,6-tribromophenyl in which one to three hydrogen atoms of the phenyl group are substituted with bromine is given. In this way, the phenyl group may be, for example, a 2,4-dibromophenyl group or a 2,6-dibromophenyl group in which two hydrogen atoms at any position are substituted with bromine. The phenyl group may be, for example, a 4-bromophenyl group or a 2-bromophenyl group in which one hydrogen atom at any position is substituted with bromine. The phenyl group may be, for example, a 2,4-dichlorophenyl group or a 2,6-dichlorophenyl group in which a hydrogen atom at any position is substituted with a halogen atom such as chlorine. The phenyl group may be, for example, a 4-chlorophenyl group or a 2-chlorophenyl group in which a hydrogen atom at any position is substituted with a halogen atom such as chlorine or other flame retardant element.

[0026] Lignocellulose contains cellulose and lignin. Lignocellulose produced by defibrating wood pieces is commercially available. For example, such commercially available lignocellulose can be used. Instead of commercially available lignocellulose, lignocellulose produced by defibrating wood by a known method can be used.

[0027] The content of flame-retardant lignocellulose in the water-based paint is not particularly limited. When the content of flame-retardant lignocellulose increases, the transparency of the coating film tends to decrease. In applications where the transparency of the coating film is important, it is preferable to contain 1 to 30 mass % or 1 to 15 mass % of flame-retardant lignocellulose. The above content is a value obtained by converting the content of flame-retardant lignocellulose into solid content.

[0028] The above-mentioned water-based paint can form a coating film having a thickness of 50 μm after solidification, in which the light transmittance at wavelengths of 450 nm, 565 nm, and 625 nm is, for example, 60% or more, 70% or more, or 80% or more. The upper limit of the transmittance is not particularly limited, but is, for example, 95% or less, or 90% or less.

[0029] Water-based paints are imparted with flame retardancy by blending flame retardant lignocellulose. The physical properties of water-based paints blended with flame retardant lignocellulose are not inferior to, and are in fact improved from, water-based paints that do not contain flame retardant lignocellulose. For example, the tensile strength of water-based paints blended with flame retardant lignocellulose can be increased, for example, up to four times that of water-based paints that do not contain flame retardant lignocellulose, depending on the amount of flame retardant lignocellulose blended.

[0030] Water-based paints may be used without adding pigments or dyes, or may be used with the addition of pigments or dyes. In the case of paints without adding pigments or dyes, a transparent coating film can be formed. In this case, a coating film that makes use of the characteristics of the base, such as wood grain, can be formed. Similarly, when dyes are added, a coating film that makes use of the characteristics of the base can be formed. When dyes or pigments are added, the coating film formed by solidifying water-based paints that do not contain dyes or paints is transparent, so that the intended color can be imparted.

[0031] In addition to the above components, the water-based paint may contain additives such as a pigment dispersant, an antifoaming agent, an anti-settling agent for the pigment, or a leveling agent that imparts smoothness to the coating film. The water-based paint may also contain a solvent, such as an alcohol solvent such as ethanol or a ketone solvent such as acetone, within a range not exceeding the content of water, which is the main liquid component. EXAMPLES

[0032] The water-based paint of the present invention will be described below with reference to examples. Each of the examples shown below is merely a limited example of the present invention, and the technical scope of the present invention is not limited to the examples shown.

[0033] [Flame retardant treatment of lignocellulose] The following N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid) tetra(2,4,6-tribromophenyl) was synthesized by a method similar to that described in JP 2020-11924 A. By a method similar to that described in the above publication, lignocellulose chemically modified with the above-mentioned synthetic product was obtained as shown in the following [Formula 1]. Note that CellFiM L45 manufactured by Mori Machinery Co., Ltd. was used as the lignocellulose. By this method, a water-dispersed slurry was obtained in which 77.52% by mass was water and the remainder was solids, and the dry weight was 1.03 g. [Formula 1] TIFF0007665189000005.tif56170

[0034] [Example 1] The water-dispersed slurry prepared by the above method was added to an aqueous polyurethane paint so that the content of lignocellulose modified with N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid)tetra(2,4,6-tribromophenyl) (hereinafter referred to as flame-retardant lignocellulose) was 5.0% by mass, and the mixture was stirred overnight with a stirrer to prepare an aqueous paint according to Example 1. The content was calculated as a solid matter excluding the liquid content. As the aqueous polyurethane paint, Yuton AQUA SC91 from Gengen Chemical Industry Co., Ltd. was used. This aqueous polyurethane paint contains 34.3% by mass of acrylic urethane emulsion, 55.2% by mass of water, 3.9% by mass of alcohol, 4.9% by mass of ketone, and 1.7% by mass of additives as resin content.

[0035] [Example 2] The aqueous paint of Example 2 was prepared in the same manner as Example 1, except that the aqueous dispersion slurry prepared by the above method was added to an aqueous polyurethane paint so that the content of flame-retardant lignocellulose was 7.5 mass% in terms of solid matter.

[0036] [Example 3] The aqueous paint of Example 2 was prepared in the same manner as Example 1, except that the aqueous dispersion slurry prepared by the above method was added to the aqueous polyurethane paint so that the cellulose content of the flame-retardant rig was 10.0 mass% in terms of solid matter.

[0037] [Comparative Example 1] A coating material according to Comparative Example 1 was prepared in the same manner as in Example 1, except that the flame-retardant lignocellulose prepared by the above method was not blended. That is, the content of the water-dispersed slurry was 0 mass %.

[0038] [Comparative Example 2] A paint according to Comparative Example 2 was prepared in the same manner as in Example 1, except that the water-based polyurethane paint was changed to an oil-based polyurethane paint, and a solid obtained by filtering and drying an aqueous dispersion slurry containing flame-retardant lignocellulose was blended with the oil-based polyurethane paint. The content of flame-retardant lignocellulose was set to 5.0% by mass. As the oil-based polyurethane paint, Yuton M L-45 from Gengen Chemical Industry Co., Ltd. was used. This oil-based polyurethane paint contains 42.0% by mass of moisture-curing polyurethane resin, 29.0% by mass of aliphatic hydrocarbon-based solvent, and 29.0% by mass of acetate-based solvent as the resin content. [Comparative Example 3] The paint of Comparative Example 3 was prepared in the same manner as Comparative Example 2, except that the flame-retardant lignocellulose prepared by the above method was added to an oil-based polyurethane paint so that its content was 10.0 mass%.

[0039] [Comparative Example 4] A coating material according to Comparative Example 1 was prepared in the same manner as in Comparative Example 2, except that the flame-retardant lignocellulose prepared by the above method was not blended. In other words, the content of the flame-retardant lignocellulose was 0 mass%.

[0040] [Preparation of test specimens] The water-based paints according to the above-mentioned examples and the paints according to the comparative examples were each poured into a petri dish and left to stand overnight. After that, the film-like test pieces were placed in a vacuum dryer with the petri dish and dried overnight at 40° C. The dried film was peeled off from the petri dish to obtain a film-like test piece.

[0041] [Tensile test] Samples with a width of 4 mm, a length of 12 mm, and a thickness of 0.2 mm were cut out from each of the test pieces according to the above examples and each of the test pieces according to the above comparative examples. The samples were stretched at 10 mm / min at room temperature to examine the relationship between strain and stress. The results are shown in Figures 1 and 2.

[0042] [Light transmittance]

[0043] The transmittance of light having a wavelength of 200 nm to 900 nm was measured for each test piece of each Example and Comparative Example using a spectrophotometer (product number: V-730BIO) manufactured by JASCO Corporation. The spectrophotometer system can measure if there is an area where light hits with a size of 1 cm. The scanning speed for changing the wavelength was 200 nm / min, the data interval was 0.5 nm, and the number of times (accumulation number) of measurement data was acquired at each wavelength was 3 times. Since the thickness of the test piece varied in the range of 40 to 60 μm, the obtained transmittance (%) value was corrected to correspond to a sample thickness of 50 μm by the following formula. The results are shown in the graphs of Figures 3 and 4. Note that Figure 4 is a graph showing the relationship between the light transmittance at a wavelength of 550 nm and the content of lignocellulose modified with N,N'-(6-amino-1,3,5-triazine-2,4-diyl)bis(phosphoramidic acid)tetra(2,4,6-tribromophenyl). (correction formula) x = 100 × exp(ln(actual transmittance (%) / 100) × 50 (μm) / sample thickness (μm))

[0044] [Test using a cone calorimeter] A test piece for a cone calorimeter was prepared by the following method. The paint of each Example or Comparative Example was applied to a stainless steel plate of 10 cm x 10 cm x 0.50 cm so that the total weight of the paint before drying and dilution was 1 g. Since the viscosity of the paint was high at the time of application, water was added to each paint to dilute it and apply it to the stainless steel plate. Then, it was dried overnight to form a coating film on the stainless steel plate. Then, it was further vacuum dried at 40°C overnight to prepare a test piece.

[0045] For each test piece prepared above, the total heat generation (kW / m 2 ) and heat release rate (MJ / m 2 The radiation amount was measured at 50kW / m 2 and the heater temperature is about 750°C. The relationship between the total heat generation amount and the time elapsed after the test piece was heated is shown in Figures 5 and 6. The relationship between the heat generation rate and the time elapsed after the test piece was heated is shown in Figures 7 and 8.

[0046] As can be seen from the results in Figure 1, in the case of the aqueous paint containing lignocellulose modified with the above-mentioned flame-retardant compound (hereinafter referred to as flame-retardant lignocellulose), as the content of flame-retardant lignocellulose increases, the distortion of the sample at break decreases and the stress value at break increases. In the sample of Example 3, the stress value was about twice as high as that of the sample of Comparative Example 1.

[0047] As can be seen from the results in Figure 2, in the case of oil-based paints containing the above-mentioned flame-retardant lignocellulose, the addition of flame-retardant lignocellulose reduces the stress value at the time of breakage of the sample, and also reduces the strain value at the time of breakage of the sample, impairing the physical properties of the coating film.

[0048] As can be seen from the results in Figure 3, the test pieces made of the water-based paints of Examples 1 to 3 all had a light transmittance of 60% or more at wavelengths of 450 nm, 565 nm, and 625 nm in the solidified coating film with a thickness of 50 μm. As can be seen from this, the water-based paint containing the above-mentioned flame-retardant lignocellulose has a high visible light transmittance and can produce a coating film with high transparency when no pigment or dye is added. In addition, as shown in Figure 4, it can be seen that as the content of flame-retardant lignocellulose increases, the visible light transmittance tends to decrease, albeit gradually.

[0049] Fig. 9 shows photographs of the test pieces of Example 3, Comparative Example 1, Comparative Example 3, and Comparative Example 4. As is clear from the photographs in Fig. 9, the test piece of Example 3 was transparent, similar to the coating film of the water-based paint of Comparative Example 1, which did not contain flame-retardant lignocellulose.

[0050] In the test piece according to Comparative Example 3, which contains the flame-retardant lignocellulose, aggregates were observed. The paint was not suitable for use.

[0051] As can be seen from the results in Figures 5 and 7, in the aqueous paint containing the above-mentioned flame-retardant lignocellulose, the higher the content of flame-retardant lignocellulose, the smaller the total heat generation amount and the smaller the peak heat generation rate.

[0052] As can be seen from the results of Figures 6 and 8, in the oil-based paint containing the above-mentioned flame-retardant lignocellulose, even if the content of flame-retardant lignocellulose is increased, there is no improvement in the total heat generation amount and heat generation rate compared to the oil-based paint of Comparison Example 4, which does not contain flame-retardant lignocellulose.

Claims

1. The water-based paint contains lignocellulose modified with a flame-retardant compound having the structure of the following [Chemical Formula 1], water as a volatile component, and a synthetic resin as a component that forms a coating film. 【Chemistry 1】 [However, R １ Or R ３ Two of the groups are the same or different, and are represented by the following formula (2): R １ Or R ３ The remaining one is lignocellulose. 【Chemistry 2】 [However, R ４ and R ５ are a group that does not contain a flame-retardant element or an aryl group substituted with a group that contains a flame-retardant element, and may be the same or different.

2. 2. The aqueous paint according to claim 1, comprising 1 to 30 mass % of the lignocellulose modified with the flame retardant compound.

3. 3. The aqueous coating material according to claim 1, wherein the light transmittance of a solidified coating film having a thickness of 50 μm is at least 60% at wavelengths of 450 nm, 565 nm and 625 nm.

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