Inorganic fiber reinforcement-based flame-retardant reconstituted bamboo and preparation method thereof

Abstract

The invention relates to the technical field of bamboo processing, in particular to flame-retardant recombined bamboo based on inorganic fiber reinforcement and a preparation method of the flame-retardant recombined bamboo. The preparation method comprises the following steps: mixing silane-grafted inorganic fibers with phenolic resin to prepare inorganic fiber modified phenolic resin; and the recombined bamboo unit soaked with the flame retardant solution is soaked in the inorganic fiber modified phenolic resin, taken out, dried and subjected to assembly hot press forming, and the flame-retardant recombined bamboo is obtained. According to the invention, the phosphorus-boron composite system and the inorganic fiber are respectively utilized to improve the flame retardance of the inner-layer recombined bamboo unit and the heat-resistant charring property of the adhesive layer, so that the ignition time of the flame-retardant recombined bamboo can be prolonged, and the peak value of the heat release rate is obviously reduced. And meanwhile, the inorganic fibers can achieve the effect of enhancing the mechanical property of the flame-retardant recombined bamboo. In addition, the preparation method of the flame-retardant recombined bamboo is easy and convenient to implement, low in cost and remarkable in effect, and has great popularization value.

Description

Technical Field

[0001] The invention relates to the technical field of bamboo material processing, and in particular to a flame-retardant reconstituted bamboo based on inorganic fiber reinforcement and a preparation method thereof. Background Art

[0002] Recombined bamboo is a new type of bamboo-based composite material made by bamboo materials through decomposition and directional reorganization. Due to its excellent physical and mechanical properties, it has been widely used in indoor and outdoor floors, furniture, structural buildings, exterior wall panels and other fields. However, recombined bamboo is prone to fire under the influence of external heat or fire sources and cannot meet the requirements of B1 flame retardant standards, which greatly limits the promotion of recombined bamboo in the construction field.

[0003] The bamboo material is prepared into reconstituted bamboo units by decomposition, and then impregnated with phenolic resin and hot pressed to obtain reconstituted bamboo. The flame retardant treatment of reconstituted bamboo is mainly achieved by applying flame retardants during the preparation process. The prior art basically involves impregnating a flame retardant solution or suspension into the reconstituted bamboo units under normal pressure or negative pressure before dipping, thereby preparing flame retardant reconstituted bamboo.

[0004] Previous studies have found that the combination of multiple flame retardant elements is an effective way to improve the efficiency of flame retardants. For example, phosphorus-based flame retardants, alkaline boron compounds and silicon-containing inorganic minerals all have excellent synergistic flame retardant effects. For example, CN102152348A discloses a method for producing flame-retardant reconstituted bamboo plywood, which uses a flame retardant solution containing phosphorus / boron / silicon / transition metal chelates to impregnate bamboo strips, and then applies melamine-modified phenolic or urea-formaldehyde fireproof glue to prepare flame-retardant reconstituted bamboo plywood.

[0005] However, traditional flame retardant treatment methods and flame retardant systems are inefficient and require large amounts of application. At the same time, inorganic salt flame retardants such as ammonium polyphosphate mainly exhibit layering, blending and filling effects with reconstructed bamboo units and phenolic resins, affecting the formation of high-quality adhesive layers and leading to the deterioration of the physical and mechanical properties of reconstructed bamboo, which seriously affects the application of reconstructed bamboo in the construction field.

[0006] Therefore, how to provide a flame-retardant reconstituted bamboo with high flame retardant efficiency, low amount of flame retardant added and excellent mechanical properties has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for preparing flame retardant reconstituted bamboo, comprising: The inorganic fiber grafted with silane is mixed with phenolic resin to prepare the inorganic fiber modified phenolic resin; The reconstructed bamboo unit soaked in the flame retardant solution is immersed in the inorganic fiber modified phenolic resin, taken out and dried, and then assembled and hot-pressed to obtain the flame retardant reconstructed bamboo.

[0008] The present invention introduces flame retardants into reconstituted bamboo units and inorganic fibers into phenolic resin networks respectively, and two flame retardant components with different functions play a synergistic flame retardant role. The inorganic fibers can play a fiber reinforcement role while improving the heat resistance and carbonization stability of the phenolic resin, thereby improving the mechanical properties of the reconstituted bamboo. The composite flame retardant system catalyzes the dehydration and carbonization of the inner layer reconstituted bamboo units, thereby reducing the generation of combustible gases. Through the synergistic effect of the two, the mechanical strength is improved while the flame retardant properties of the reconstituted bamboo are improved. Moreover, the introduction of inorganic fibers can replace the use of part of the flame retardant, thereby reducing the amount of flame retardant added.

[0009] Preferably, the silane-grafted inorganic fiber is prepared by mixing inorganic fiber and aminoorganosilane in a solvent and then heating the mixture.

[0010] Preferably, the inorganic fiber is placed in a mixed solution containing 20-80 parts of water, 2-20 parts of aminoorganosilane and 20-80 parts of anhydrous ethanol, placed in a 60°C-90°C water bath and stirred and heated for 1-6 hours, washed with ethanol, filtered and dried to obtain the inorganic fiber grafted with silane.

[0011] Preferably, the immersion time is 5-20 minutes.

[0012] Preferably, the inorganic fibers include but are not limited to artificial inorganic fibers, natural mineral fibers and the like.

[0013] Preferably, the inorganic fiber is at least one of glass fiber, aluminum silicate fiber, sepiolite fiber and basalt fiber.

[0014] Preferably, the aminoorganosilane is at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0015] Preferably, the solvent is an alcohol solution, preferably an ethanol aqueous solution.

[0016] Preferably, the inorganic fiber grafted with silane accounts for 1%-15% (e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%) of the solid mass in the phenolic resin.

[0017] Preferably, the flame retardant solution contains a phosphorus-containing inorganic flame retardant and borax.

[0018] Preferably, the weight ratio of the phosphorus-containing inorganic flame retardant to borax is (5-40): (3-25).

[0019] More preferably, the weight ratio of the phosphorus-containing inorganic flame retardant to borax is (15-30):(5-10).

[0020] Preferably, the phosphorus-containing inorganic flame retardant is at least one of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium polyphosphate.

[0021] Preferably, a flame retardant solution is prepared by using 5-40 parts of a phosphorus-containing inorganic flame retardant, 3-25 parts of borax, and 80-120 parts of water, and the reconstructed bamboo unit is immersed in the flame retardant solution for flame retardant treatment.

[0022] Preferably, the reconstructed bamboo unit is at least one of bamboo filaments, bamboo bundles, and fiberized bamboo veneers.

[0023] Preferably, the drying is performed to a moisture content of 8%-15%.

[0024] Most preferably, the preparation method comprises: 15-30 parts of ammonium polyphosphate, 5-10 parts of borax and 110-130 parts of water are prepared into a flame retardant solution, and the reconstructed bamboo unit is immersed in the flame retardant solution and dried for later use.

[0025] 25-35 parts of basalt fiber are placed in a mixed solution of 45-55 parts of water, 3-8 parts of γ-aminopropyl trimethoxysilane, and 45-55 parts of anhydrous ethanol, and stirred and heated in a water bath at 55°C-65°C, and washed, filtered, and dried to obtain γ-aminopropyl trimethoxysilane-modified basalt fiber. γ-aminopropyl trimethoxysilane-modified basalt fiber is added to phenolic resin with a solid content of 20%-30% and stirred evenly, and the mass of γ-aminopropyl trimethoxysilane-modified basalt fiber accounts for 4%-6% of the solid mass of phenolic resin.

[0026] The air-dried reconstructed bamboo units are soaked in phenolic resin containing γ-aminopropyltrimethoxysilane-modified basalt fiber and dried to a moisture content of 8%-15%. They are stacked in a mold and prepared into flame-retardant reconstructed bamboo under a hot pressing temperature of 140℃-160℃, a hot pressing time of 0.8-1.2min / mm, and a hot pressing pressure of 20-30MPa.

[0027] Furthermore, the present invention provides flame-retardant reconstituted bamboo prepared by the preparation method of any of the above embodiments.

[0028] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a flame-retardant reconstructed bamboo with high flame-retardant efficiency, low amount of flame retardant added and excellent mechanical properties. The phosphorus-boron composite system and inorganic fiber are used to improve the flame retardancy of the inner layer reconstructed bamboo unit and the heat-resistant carbonization property of the glue layer, respectively, so that the ignition time of the flame-retardant reconstructed bamboo can be prolonged and the peak value of the heat release rate can be significantly reduced. At the same time, the inorganic fiber is dispersed in the phenolic resin to achieve the effect of enhancing the mechanical properties of the flame-retardant reconstructed bamboo. Compared with ordinary flame-retardant reconstructed bamboo, the shear strength and bending resistance of the flame-retardant reconstructed bamboo of the present invention are significantly improved. In addition, the preparation method of the flame-retardant reconstructed bamboo is simple to implement, low in cost, and has significant effects, and has great promotion value. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The "parts" in the following embodiments represent parts by weight, and the units can be g, kg, etc.

[0030] If no specific techniques or conditions are specified in the examples, all are carried out according to conventional methods or the techniques or conditions described in the literature in the field, or according to the product instructions. If no manufacturer is specified for the reagents and instruments used, all are conventional products that can be purchased through regular channels.

[0031] Example 1

[0032] This embodiment provides a flame retardant reconstituted bamboo, and the preparation method thereof is as follows: 30 parts of ammonium polyphosphate, 10 parts of borax and 120 parts of water were prepared into a flame retardant solution, and the reconstructed bamboo units of the Phyllostachys cycads were immersed in the flame retardant solution for 2 hours and then dried for later use.

[0033] 30 parts of sepiolite fiber were placed in a mixed solution of 50 parts of water, 5 parts of γ-aminopropyl triethoxysilane and 50 parts of anhydrous ethanol, placed in a 60°C water bath, stirred and heated for 1 hour, washed with ethanol, filtered and dried to obtain γ-aminopropyl triethoxysilane-modified sepiolite fiber. γ-aminopropyl triethoxysilane-modified sepiolite fiber was added to phenolic resin with a solid content of 20% and stirred evenly, and the mass of γ-aminopropyl triethoxysilane-modified sepiolite fiber accounted for 5% of the solid mass of phenolic resin.

[0034] The air-dried reconstructed bamboo unit was immersed in phenolic resin containing γ-aminopropyltriethoxysilane modified sepiolite fiber for 10 minutes, taken out and drained, and dried to a moisture content of 10%. It was stacked in a mold and prepared into a flame-retardant reconstructed bamboo with a thickness of 10 mm under a hot pressing temperature of 150°C, a hot pressing time of 1 min / mm, and a hot pressing pressure of 20 MPa.

[0035] Example 2

[0036] This embodiment provides a flame retardant reconstituted bamboo, the preparation method of which is different from that of embodiment 1 only in that: The mass of the γ-aminopropyltriethoxysilane modified sepiolite fiber accounts for 10% of the solid mass of the phenolic resin.

[0037] Example 3

[0038] This embodiment provides a flame retardant reconstituted bamboo, the preparation method of which is different from that of embodiment 1 only in that: The sepiolite fiber was replaced with glass fiber, and γ-aminopropyl triethoxysilane was replaced with γ-aminopropyl trimethoxysilane to obtain γ-aminopropyl trimethoxysilane modified glass fiber. Subsequently, γ-aminopropyl trimethoxysilane modified glass fiber was used to replace γ-aminopropyl triethoxysilane modified sepiolite fiber to prepare flame retardant reconstituted bamboo.

[0039] Example 4

[0040] This embodiment provides a flame retardant reconstituted bamboo, the preparation method of which is different from that of embodiment 1 only in that: The sepiolite fiber was replaced with aluminum silicate fiber, and γ-aminopropyl triethoxysilane was replaced with N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane to prepare N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane-modified aluminum silicate fiber. Subsequently, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane-modified aluminum silicate fiber was used to replace γ-aminopropyl triethoxysilane-modified sepiolite fiber to prepare flame-retardant reconstituted bamboo.

[0041] Example 5

[0042] This embodiment provides a flame retardant reconstituted bamboo, the preparation method of which is different from that of embodiment 1 only in that: The sepiolite fiber was replaced by basalt fiber, and γ-aminopropyl triethoxysilane was replaced by γ-aminopropyl trimethoxysilane to obtain γ-aminopropyl trimethoxysilane-modified basalt fiber. Subsequently, γ-aminopropyl trimethoxysilane-modified basalt fiber was used to replace γ-aminopropyl triethoxysilane-modified sepiolite fiber to prepare flame-retardant reconstituted bamboo.

[0043] Comparative Example 1

[0044] This comparative example provides a recombinant bamboo, which is untreated recombinant bamboo, and the preparation method is as follows: The reconstructed bamboo units of the bamboo were soaked in phenolic resin with a solid content of 20% for 10 minutes, taken out and drained, and dried to a moisture content of 10%. They were stacked in a mold and prepared into reconstructed bamboo with a thickness of 10 mm under a hot pressing temperature of 150°C, a hot pressing time of 1 min / mm, and a hot pressing pressure of 20 MPa.

[0045] Comparative Example 2

[0046] This comparative example provides a flame retardant reconstituted bamboo, which is a common flame retardant reconstituted bamboo, and the preparation method is as follows: 30 parts of ammonium polyphosphate, 10 parts of borax, and 120 parts of water were prepared into a flame retardant solution, and the bamboo reconstructed unit of the Chinese bamboo was immersed in the flame retardant solution for 2 hours, and dried for use. The reconstructed bamboo unit after the flame retardant treatment was soaked in a phenolic resin with a solid content of 20% for 10 minutes, taken out and drained, and dried to a moisture content of 10%. Stacked in a mold, a flame retardant reconstructed bamboo with a thickness of 10 mm was prepared under a process of hot pressing temperature of 150°C, hot pressing time of 1 min / mm, and hot pressing pressure of 20 MPa.

[0047] Test example

[0048] This test example tests the performance of the reconstructed bamboo of the above-mentioned embodiment and comparative example, and the specific steps are as follows: the pressed reconstructed bamboo is sawn into test pieces of a certain size, and the flame retardant performance is tested using a cone calorimeter, and the mechanical properties are tested using a universal mechanical testing machine. The test results are shown in Table 1.

[0049] Table 1 Flame retardant properties and mechanical properties of reconstructed bamboo

[0050] The peak values ​​of the heat release rate of all the embodiments of the present invention are lower than that of the comparative examples, and the ignition time and limiting oxygen index (LOI) are higher than those of comparative examples 1 and 2, indicating that the flame retardant properties of the flame retardant reconstructed bamboo of the embodiments are greatly improved compared with the untreated reconstructed bamboo and the ordinary flame retardant reconstructed bamboo. At the same time, the horizontal shear strength and bending strength of the embodiments are better than the ordinary flame retardant reconstructed bamboo of comparative example 2, and are equivalent to those of comparative example 1 (i.e., the reconstructed bamboo not subjected to flame retardant treatment), indicating that the mechanical properties of the flame retardant reconstructed bamboo of the embodiments are improved compared with the mechanical properties of the traditional flame retardant reconstructed bamboo.

[0051] In summary, the flame retardant properties and mechanical properties of the flame retardant reconstructed bamboo prepared by the inorganic fiber reinforcement strategy proposed in the present invention are significantly improved compared with the traditional flame retardant reconstructed bamboo. At the same time, the strategy of the present invention is simple to implement, low in cost, and effective, and is suitable for large-scale promotion.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing flame retardant reconstituted bamboo, characterized in that: include: The inorganic fiber grafted with silane is mixed with phenolic resin to prepare the inorganic fiber modified phenolic resin; The reconstructed bamboo unit soaked in the flame retardant solution is immersed in the inorganic fiber modified phenolic resin, taken out and dried, and then assembled and hot-pressed to obtain the flame retardant reconstructed bamboo.

2. The preparation method according to claim 1, characterized in that: The inorganic fiber grafted with silane is prepared by mixing inorganic fiber and aminoorganosilane in a solvent and then heating the mixture.

3. The preparation method according to claim 2, characterized in that: The inorganic fiber is at least one of glass fiber, aluminum silicate fiber, sepiolite fiber and basalt fiber.

4. The preparation method according to claim 2, characterized in that: The aminoorganosilane is at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

5. The preparation method according to claim 2, characterized in that: The solvent is an alcohol solution, preferably an ethanol aqueous solution.

6. The preparation method according to claim 1, characterized in that: The inorganic fiber grafted with silane accounts for 1% to 15% of the solid mass in the phenolic resin.

7. The preparation method according to claim 1, characterized in that: The flame retardant solution contains a phosphorus-containing inorganic flame retardant and borax; preferably, the weight ratio of the phosphorus-containing inorganic flame retardant to the borax is (5-40): (3-25).

8. The preparation method according to claim 7, characterized in that: The phosphorus-containing inorganic flame retardant is at least one of diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium polyphosphate.

9. The preparation method according to claim 1, characterized in that: The reconstructed bamboo unit is at least one of bamboo filaments, bamboo bundles, and fiberized bamboo veneers; and / or the drying is performed to a moisture content of 8%-15%.

10. The flame retardant reconstituted bamboo obtained by the preparation method according to any one of claims 1 to 9.

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