Flame-retardant super-thin fiberboard and method for manufacturing the same

Abstract

Provided are a fire-retardant ultra-thin fiberboard and a preparation method thereof, which can bring excellent fire-retardant performance and ensure mechanical properties. PBTC-HCCN fire-retardant agents are added to wood fibers in the sizing and paving processes for preparing the ultra-thin fiberboard, and the molecular structural formula is as follows.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flame-retardant treatment of ultra-thin fiberboard, and in particular to a flame-retardant ultra-thin fiberboard and a preparation method thereof. BACKGROUND

[0002] The production technology of ultra-thin fiberboard is difficult, and currently there is little research on its flame-retardant treatment. Two commonly conceivable flame-retardant treatment methods are available.

[0003] One is to perform flame-retardant impregnation treatment on the prepared fiberboard. However, this method is high in energy consumption and generates a large amount of waste liquid, and is not suitable for large-scale production.

[0004] The other is to add a flame retardant to the fiber raw material. In the inventors' previous research, a commonly used flame retardant such as 15% of ammonium polyphosphate (APP), melamine (MEL), melamine cyanurate (MCA), and melamine phosphate (MPP) was added to prepare an ultra-thin flame-retardant fiberboard with a thickness of 1.5 mm. While ensuring the improvement of flame-retardant performance, it is difficult to ensure that the static bending strength and water absorption thickness expansion rate in the mechanical properties meet the relevant requirements of T / CNFPIA3007-2019 "Ultra-thin high-density fiberboard". The specific test data are as follows:

[0005] Standard requirements APP MEL MCA MPP Oxygen index - 33 28 30.5％ 34％ Static bending strength ≥ 42 MPa 42.3 42.5 41.3 41.2 Water absorption thickness expansion rate ≤35％ 35.1 34.3 34.1 35.5 SUMMARY

[0006] The present application aims to provide a flame-retardant ultra-thin fiberboard capable of ensuring mechanical properties and a preparation method thereof.

[0007] According to the preparation method of the flame-retardant ultra-thin fiberboard, PBTC-HCCN flame retardants are added to wood fibers in the sizing and laying processes for preparing the ultra-thin fiberboard, and the molecular structural formula of PBTC-HCCN is as follows:

[0008]

[0009] Preferably, the mass ratio of PBTC-HCCN added in the sizing and laying processes is (8-10):(2-2.5) respectively.

[0010] Preferably, the sizing process comprises: adding wood fibers obtained by a hot grinding method with a moisture content of 13-13.5% and PBTC-HCCN accounting for 8-10% of the mass of the wood fibers into a glue mixer, and applying melamine modified urea-formaldehyde resin adhesive accounting for 11-13% of the mass of the wood fibers after starting the glue mixer.

[0011] More preferably, the laying process comprises: applying PBTC-HCCN flame retardants accounting for 2-2.5% of the mass of the wood fibers to the wood fibers after gluing above the laying bin, mixing uniformly under the action of a throwing roller, and laying.

[0012] In addition, the sizing process is a melamine modified urea-formaldehyde resin adhesive.

[0013] In addition, the hot pressing process has a hot pressing time of 8-10 min, a hot pressing pressure of 2-4 MPa, a hot pressing temperature of 190-220℃, a control plate thickness of 15 mm, and a plate density of 850 g / cm 3 .

[0014] The PBTC-HCCN flame retardant is prepared by the following method:

[0015] K2CO3 powder, hexachlorocyclotriphosphazene and acetaminophen with a molar ratio of 1:(7.0-7.2) are dissolved in tetrahydrofuran, heated to 80℃ and reacted for 72h, then 80% mass concentration of sodium hydroxide aqueous solution is added and the reaction is continued for 10h, and the reaction product A is obtained by filtration; reactant A and 2-phosphonic acid butane-1,2,4-tricarboxylic acid with a molar ratio of 1:(9.2-10.2) are dissolved in acetone and reacted at 70℃ for 24h, the filtrate is obtained by filtration and the solvent is suspended and evaporated to obtain PBTC-HCCN.

[0016] The application also aims to provide a flame-retardant ultra-thin fiberboard prepared by the above method.

[0017] The flame retardant PBTC-HCCN provided by the application overcomes the influence of the previous flame retardant on the performance of the fiberboard and can ensure the combustion performance. The multi-terminal and multi-directional COOH in the flame retardant combines with the hydroxyl group of the wood fiber, and the flame retardant participates in the molecular structure of the adhesive curing process. The flame retardant is added to the adhesive in the sizing process and added in the paving process. Avoiding too large amount of one-time addition makes the moisture of the fiber absorbed too much by the flame retardant, which affects the bonding strength, and ensures more uniform application. DETAILED DESCRIPTION

[0018] In the process description of the present application, some values related to temperature or pressure, process change rate, etc. will be mentioned, for example, in terms of temperature, those skilled in the art should know that when it is mentioned that a reaction is carried out at a certain temperature, the actual meaning is that the control of the temperature is not absolutely constant, and there may even be a certain fluctuation, which may exceed one degree or more in some cases, as long as the purpose can be achieved. The range of temperature change and the accuracy of temperature control are based on the scope that those skilled in the art can understand. In addition, the temperature defined in this paper can be the input of the temperature control on the equipment used, and the temperature at a certain point in the actual process depends on the particularity of the machine equipment and the condition at that time. The defined temperature can also be the target of the operator's instruction, which may involve a temperature change time in the actual control, and even include a process of repeatedly fluctuating up and down, for example, when the temperature is detected to be lower than the defined temperature, the reactor is heated, and when it is higher than the defined temperature, the reactor is cooled, so as to maintain the instruction temperature as a whole.

[0019] In the present application, the numerical range "A~B" means A or more (greater than or equal to A) and B or less (less than or equal to B) unless otherwise specified. When referring to the concept of normal temperature or room temperature, it usually refers to between 22~25℃, and sometimes it may be between 20~28℃ depending on the process. Different fields in the actual industry have different understandings of normal temperature or room temperature, but for the implementation and application of the patent law, it should be considered as limited to achieving the purpose of the invention, and should not be understood as a narrow experience range in a certain field. In the present application, some processes are not mentioned as temperature or room temperature, which should be considered as being carried out at normal temperature or room temperature, and those skilled in the art do not need special understanding to control the process conditions, unless otherwise specified or those skilled in the art should understand the special circumstances.

[0020] The preparation method of the flame-retardant ultra-thin fiber board provided by the present application adds PBTC-HCCN flame retardant to wood fibers in the gluing and paving processes of preparing the ultra-thin fiber board, and the molecular structural formula of PBTC-HCCN is:

[0021]

[0022] The PBTC-HCCN flame retardant is prepared by the following method:

[0023] K2CO3 powder, hexachlorocyclotriphosphazene and acetaminophen with a molar ratio of 1 :(7.0-7.2) were dissolved in tetrahydrofuran, the temperature was raised to 80°C and reacted for 72 h, then 80% mass concentration of sodium hydroxide aqueous solution was added and reacted for 10 h, and the reaction product A was obtained by filtration; the reaction product A and 2-phosphonobutane-1, 2, 4-tricarboxylic acid with a molar ratio of 1 :(9.2-10.2) were dissolved in acetone and reacted at 70°C for 24 h, the filtrate was obtained by filtration and the solvent was suspended and evaporated to obtain PBTC-HCCN.

[0024] In the preparation of PBTC-HCCN, the amount of K2CO3 added can be selected from the following: the molar ratio of hexachlorocyclotriphosphazene to K2CO3 is 1 :(9.5-10.8); those skilled in the art can select the appropriate amount according to the requirements of weak alkaline reaction.

[0025] The amount of 80% mass concentration of sodium hydroxide aqueous solution added can be selected from the following: the molar ratio of hexachlorocyclotriphosphazene to sodium hydroxide aqueous solution is 1:10; those skilled in the art can select the appropriate amount according to the requirements of hydrolysis capacity.

[0026] Specific preparation of an example PBTC-HCCN:

[0027] Preparation Example 1

[0028] 1 mmol of hexachlorocyclotriphosphazene, 7.2 mmol of acetaminophen, and 9.5 mmol of K2CO3 powder were dissolved in a three-necked flask containing 200 mL of tetrahydrofuran, the temperature was raised to 80°C, and reacted for 72 h, then 200 mL of sodium hydroxide aqueous solution was added and reacted for 10 h, and the reaction product A was obtained by filtration. 1 mmol of the reaction product A and 9.2 mmol of 2-phosphonobutane-1, 2, 4-tricarboxylic acid were placed in a three-necked flask containing 500 mL of acetone, and reacted at 70°C for 24 h, then the filtrate was obtained by filtration and evaporated by a rotary evaporator to obtain white powder PBTC-HCCN. The yield of PBTC-HCCN was 78%, and the solubility in 100 g of water was 1.2 g.

[0029] Preparation Example 2

[0030] 1 mmol hexachlorocyclotriphosphazene, 7.0 mmol p-acetamidophenol, 10.8 mmol K2CO3 powder were dissolved in a three-necked flask containing 200 mL tetrahydrofuran, the temperature was raised to 80℃, and the reaction was carried out for 72 h, then 200 mL aqueous NaOH solution was added and the reaction was continued for 10 h, and the reaction product A was obtained by filtration. 1 mmol of reaction product A and 10.2 mmol of 2-phosphonobutane-1,2,4-tricarboxylic acid were placed in a three-necked flask containing 500 mL acetone, and the reaction was carried out at 70℃ for 24 h, and the filtrate was obtained by filtration and evaporated by a rotary evaporator to obtain white powder PBTC-HCCN. The yield of PBTC-HCCN was 85%, and the solubility in 100 g water was 1.0 g.

[0031] The synthesis of the PBTC-HCCN flame retardant comprises two steps:

[0032] The first step is the reaction of hexachlorocyclotriphosphazene and p-acetamidophenol:

[0033] Reaction formula 1:

[0034]

[0035] The second step is the addition of a triazine ring:

[0036] Reaction formula 2:

[0037]

[0038] The inventors designed a flame retardant starting from hexachlorocyclotriphosphazene, which is a small molecule compound with flame retardant effect. By reacting with p-acetamidophenol, the purpose of symmetrical amination is achieved, and then by further reacting with 2-phosphonobutane-1,2,4-tricarboxylic acid, PBTC-HCCN is prepared, which further increases the molecular weight. The increase of molecular weight improves the initial thermal decomposition temperature, so as to match the initial thermal decomposition temperature of wood, improve the flame retardant efficiency, and further improve the molecular weight to prevent self-agglomeration before reacting with wood. The multiple COOH groups in the flame retardant bind with the hydroxyl groups of wood fibers, and the flame retardant participates in the molecular structure of the adhesive curing during the curing process of the adhesive.

[0039] The PBTC-HCCN flame retardant is added to the wood fibers in the sizing and laying processes of the preparation of ultra-thin fiberboard, respectively. The flame retardant is added to the glue in the sizing process and a part is applied, and a part is added in the laying process. Avoiding too large amount of application at one time, the moisture of the fibers is absorbed too much by the flame retardant, which affects the bonding strength, and ensures more uniform application. Preferably, the mass ratio of PBTC-HCCN added in the sizing and laying processes is (8-10):(2-2.5).

[0040] As a specific preferred example, the sizing process comprises: adding wood fibers obtained by hot grinding with a water content of 13-13.5% and PBTC-HCCN accounting for 8-10% of the mass of wood fibers into a glue mixer, and then applying melamine modified urea-formaldehyde resin adhesive accounting for 11-13% of the mass of wood fibers after starting the glue mixer; the laying process comprises: applying PBTC-HCCN flame retardant accounting for 2-2.5% of the mass of wood fibers to the wood fibers after gluing above the laying bin, and then mixing uniformly and laying under the action of the throwing roller.

[0041] The hot grinding method mainly includes cooking and hot grinding processes, which are used as a process for obtaining wood fibers from wood materials for fiberboard production. The wood material for hot grinding treatment is generally wood chips dehydrated by water washing. The wood is softened by cooking, the water film in the cellulose gap is thickened, the intermolecular distance is increased, and the attraction is reduced, so that relative sliding under external force is facilitated. After hot grinding treatment, the wood chip moisture content is homogenized, and the fiber separation efficiency and fiber separation uniformity suitable for processing are obtained.

[0042] The laying system is completed in the laying bin, and the PBTC-HCCN flame retardant is applied to the wood fibers after gluing above the laying bin. The wood fibers after applying the flame retardant are mixed uniformly and laid under the action of the throwing roller. Since the laying system is a mature known technology, it is not described here, and only the existing structure is cited to illustrate the addition position and timing of the flame retardant.

[0043] The process for preparing ultra-thin fiberboard also includes pre-pressing, hot pressing, and post-treatment processes. The laid board blank is transported to the pre-pressing machine by the conveying belt for pre-pressing. The hot pressing time is 8-10 min, the hot pressing pressure is 2-4 MPa, the hot pressing temperature is 190-220℃, the control board thickness is 15 mm, and the board density is 850 g / cm 3 . The hot-pressed board is conveyed to the board turning frame by the conveying belt, cooled, and then stacked and packaged.

[0044] Specific preparation of wood fibers obtained by hot grinding method:

[0045] Preparation Example 3

[0046] The New Zealand radiata pine logs are flaked, and the flaked wood chips have a length, width and thickness of 5-10 cm, 5-10 cm and 1-3 cm respectively. After water washing and dehydration, the flaked wood chips are temporarily stored in the preheating buffer bin in front of the hot grinder through the closed conveying belt, and then are sent into the vertical digester for cooking and softening treatment after being extruded by the variable-diameter screw to form wood plugs. The cooking temperature is 163℃, and the cooking treatment time is 3 min. The cooked wood chips are sent into the hot grinder, and then 60# fully refined paraffin wax is added thereto in an amount of 8 kg / m 3 , to obtain pine wood fibers with a water content of 13%.

[0047] The PBTC-HCCN prepared from Preparation Example 1 was used to prepare ultra-thin fiberboard after mixing with wood fibers obtained from Preparation Example 3. According to the experimental results, it can be judged that the ultra-thin fiberboard has good flame retardant performance, and the mechanical properties can meet the standard requirements. Each experimental example tests each performance according to the same test method.

[0048] Example 1

[0049] Process: 10% PBTC-HCCN by mass was added to the glue mixer together with wood fibers with a moisture content of 13.5%, and 13% melamine modified urea-formaldehyde resin adhesive was applied in the glue mixer. 2.5% of the flame retardant was applied on the flame-retardant wood fibers after glue mixing above the paving bin, and was mixed uniformly and completed paving under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 10 min, the hot pressing pressure was 4 MPa, and the hot pressing temperature was 220℃. The flame-retardant ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0050] Wood fibers with a moisture content of 13.5% were added to the glue mixer, and 13% melamine modified urea-formaldehyde resin adhesive was applied in the glue mixer. And the paving was completed under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 10 min, the hot pressing pressure was 4 MPa, and the hot pressing temperature was 220℃. The ordinary ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0051] Performance test:

[0052]

[0053] Example 2

[0054] 8% PBTC-HCCN by mass was added to the glue mixer together with wood fibers with a moisture content of 13%, and 11% melamine modified urea-formaldehyde resin adhesive was applied in the glue mixer. 2% of the flame retardant was applied on the flame-retardant wood fibers after glue mixing above the paving bin, and was mixed uniformly and completed paving under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 8 min, the hot pressing pressure was 2 MPa, and the hot pressing temperature was 190℃. The flame-retardant ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0055] Wood fiber with water content of 13% was added into the glue mixer, and melamine modified urea-formaldehyde resin adhesive with mass ratio of 11% was applied in the glue mixer. The wood fiber was mixed and laid under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 8 min, the hot pressing pressure was 2 MPa, and the hot pressing temperature was 190 ℃. The ordinary ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0056] Performance test:

[0057]

[0058] Example 3

[0059] PBTC-HCCN with mass ratio of 9.5% and wood fiber with water content of 13.3% were added into the glue mixer, and melamine modified urea-formaldehyde resin adhesive with mass ratio of 11.5% was applied in the glue mixer. 2.2% of the flame retardant was applied on the flame-retardant wood fiber after glue mixing above the laying bin, and was mixed and laid under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 9 min, the hot pressing pressure was 2.5 MPa, and the hot pressing temperature was 210 ℃. The flame-retardant ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0060] Wood fiber with water content of 13.3% was added into the glue mixer, and melamine modified urea-formaldehyde resin adhesive with mass ratio of 11.5% was applied in the glue mixer. The wood fiber was mixed and laid under the action of the throwing roller. After pre-pressing, hot pressing was carried out, and the thickness of the board was controlled to be 1.5 mm. The hot pressing time was 9 min, the hot pressing pressure was 2.5 MPa, and the hot pressing temperature was 210 ℃. The ultra-thin fiberboard with a thickness of 1.5 mm was prepared.

[0061] Performance test:

[0062]

[0063] It should be understood that the specific embodiments described herein are merely exemplary and are not limiting to the application. The application can be variously modified within the scope of the claims. The various embodiments or examples, and combinations thereof, and combinations of the various embodiments or examples with common technical means, and new variations obtained by the application, should be considered as included in the scope of the application.

Claims

1. A preparation method of a fire-retardant ultra-thin fiberboard, characterized in that, PBTC-HCCN fire-retardant is added to wood fibers in a sizing and laying process for preparing the ultra-thin fiberboard, the PBTC-HCCN has multi-terminal and multi-directional COOH groups, and its molecular structure is: The mass ratio of PBTC-HCCN added in the sizing and laying process is (8-10):(2-2.5), The sizing process comprises: adding wood fibers with a water content of 13-13.5% obtained by a hot grinding method and PBTC-HCCN accounting for 8-10% of the mass of the wood fibers into a glue mixer, and applying melamine modified urea-formaldehyde resin adhesive accounting for 11-13% of the mass of the wood fibers after starting the glue mixer, the hot grinding method comprises a cooking and hot grinding process, The laying process comprises: applying PBTC-HCCN fire-retardant accounting for 2-2.5% of the mass of the wood fibers to the wood fibers after sizing above the laying bin, mixing uniformly and laying under the action of a throwing roller, Also included is a hot-pressing process, wherein the hot-pressing time is 8-10 min, the hot-pressing pressure is 2-4 MPa, the hot-pressing temperature is 190-220 °C, the control plate thickness is 15 mm, and the plate density is 1005-1020 Kg / m 3 .

2. The preparation method of claim 1, wherein, The PBTC-HCCN fire-retardant is prepared by the following method: K2CO3 powder, hexachlorocyclotriphosphazene and acetaminophen with a molar ratio of 1:(7.0-7.2) are dissolved in tetrahydrofuran, heated to 80℃ and reacted for 72h, then 80% mass concentration sodium hydroxide aqueous solution is added and reacted for 10h, and the reaction product A is obtained by filtration; reaction product A and 2-phosphonobutane-1,2,4-tricarboxylic acid with a molar ratio of 1:(9.2-10.2) are dissolved in acetone and reacted at 70℃ for 24h, the filtrate is obtained by filtration and the solvent is suspended and evaporated to obtain PBTC-HCCN.

3. A fire-retardant super-thin fiberboard, characterized by, The fire-retardant ultra-thin fiberboard is prepared by the preparation method of claim 1 or 2.

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