阅读说明：本技术 一种阻燃无醛密度板的制造工艺 (Manufacturing process of flame-retardant formaldehyde-free density board ) 是由 仲维龙 肖锋 腾辉 刘丛飞 于 2019-09-24 设计创作，主要内容包括：本发明公布了一种阻燃无醛密度板的制造工艺,杨树木在温度为170～180℃,蒸煮压力为9.5±0.5bar,蒸煮时间为3.5±0.3min的条件下,经蒸汽软化后被热磨机碾磨成所述木质纤维,该木质纤维须包括以下三种尺寸规格及其占比：长度2mm～5.4mm且长宽比为63～110的木质纤维占比10％～20％,长度0.125～2mm且长宽比为35～63的木质纤维占比70％～90％,剩余木质纤维的长度0.06～0.125mm且长宽比20～35；异氰酸酯40±5kg/m3,石蜡5.5±0.5kg/m3,磷系列阻燃剂57±4kg/m3,染料1.8±0.6kg/m3,混合后的物料经干燥后须使得纤维水分为7±0.5％；混合后的物料最后在热压机中依次经过五个温度区后被压制成型。本发明提供的工艺制造出来的密度板实现了内结合强度、甲醛释放量和阻燃性三方面性能的同时提升。(The invention discloses a manufacturing process of a flame-retardant formaldehyde-free density board, which is characterized in that poplar is softened by steam and ground into wood fibers by a hot grinding machine under the conditions that the temperature is 170-180 ℃, the cooking pressure is 9.5 +/-0.5 bar and the cooking time is 3.5 +/-0.3 min, wherein the wood fibers comprise the following three dimensions and proportions: 10-20% of wood fibers with the length of 2-5.4 mm and the length-width ratio of 63-110, 70-90% of wood fibers with the length of 0.125-2 mm and the length-width ratio of 35-63, and 20-35% of the rest wood fibers with the length of 0.06-0.125 mm; 40 plus or minus 5kg/m3 of isocyanate, 5.5 plus or minus 0.5kg/m3 of paraffin, 57 plus or minus 4kg/m3 of phosphorus series flame retardant and 1.8 plus or minus 0.6kg/m3 of dye, and the mixed materials are dried to ensure that the fiber moisture is 7 plus or minus 0.5 percent; and finally, the mixed materials are pressed and molded in a hot press after sequentially passing through five temperature zones. The density board manufactured by the process provided by the invention realizes the simultaneous improvement of the performances of internal bonding strength, formaldehyde release amount and flame retardance in three aspects.)

1. A process for manufacturing a flame retardant formaldehyde-free density board, comprising the steps of:

(1) preparing wood into wood fibers at high temperature and high pressure;

(2) adding an adhesive, paraffin, a flame retardant and a dye into the wood fiber, and drying;

(3) the hot press solidifies and molds the mixed wood fiber;

the method is characterized in that: in the step (1), the wood is poplar, the poplar is softened by steam and ground into the wood fiber by a hot grinding machine under the conditions that the temperature is 170-180 ℃, the cooking pressure is 9.5 +/-0.5 bar, and the cooking time is 3.5 +/-0.3 min, wherein the wood fiber comprises the following three dimensions and ratios thereof: 10-20% of wood fibers with the length of 2-5.4 mm and the length-width ratio of 63-110, 70-90% of wood fibers with the length of 0.125-2 mm and the length-width ratio of 35-63, and 20-35% of the rest wood fibers with the length of 0.06-0.125 mm;

in the step (2), the added adhesive is isocyanate, the flame retardant is a phosphorus flame retardant, and the various materials are added and mixed to meet the following requirements: isocyanate 40 +/-5 kg/m³5.5 +/-0.5 kg/m of paraffin wax³57 +/-4 kg/m of phosphorus series flame retardant³Dye 1.8 +/-0.6 kg/m³Drying the mixed material to ensure that the fiber moisture is 7 +/-0.5%;

in the step (3), the temperature of the hot press is 240 +/-5 ℃, 255 +/-5 ℃, 240 +/-5 ℃, 210 +/-5 ℃ and 140 +/-8 ℃ in sequence, and the corresponding duration is 25 +/-2 s, 21 +/-2 s, 23 +/-2 s, 28 +/-3 s and 35 +/-1 s in sequence; the pressures of the high-pressure area and the middle-pressure area of the hot press are respectively 4.5 +/-0.5N/mm²And 1. + -. 0.2N/mm²And the residence time of the high-pressure area is not less than two thirds of the total hot-pressing time.

2. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: the poplar trees are cooked and softened under the conditions that the temperature is 174-178 ℃, the cooking pressure is 9.3-9.7 bar, and the cooking time is 3.3-3.6 min.

3. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: among the wood fibers, the wood fibers with the length of 3.4-4.5 mm and the length-width ratio of 73-97 account for 13-17 percent.

4. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: among the wood fibers, the wood fibers with the length of 0.57-1.38 mm and the length-width ratio of 42-54 account for 80-85 percent.

5. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: the length of the remaining wood fibers is 0.082-0.1 mm and the length-width ratio is 24-32.

6. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: 38-43 kg/m isocyanate³5.4-5.7 kg/m paraffin wax³55 to 59kg/m of phosphorus-based flame retardant³。

7. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: the mixed material is dried to ensure that the fiber moisture is 6.8-7.3%.

8. The process of manufacturing a fire retardant aldehyde-free density board as claimed in claim 1, wherein: the temperature of the hot press is 239-243 ℃, 253-258 ℃, 236-243 ℃, 208-213 ℃ and 138-143 ℃ in sequence, and the corresponding duration is 24-25 s, 21-23 s, 22-25 s, 27-30 s and 35-36 s in sequence.

9. According to the claimsSolving 1 the manufacturing process of the flame-retardant formaldehyde-free density board, which is characterized in that: the pressures of the high-pressure area and the middle-pressure area of the hot press are respectively 4.3-4.7N/mm²And 1 to 1.1N/mm²。

Technical Field

The invention belongs to the technical field of density boards, and particularly relates to a manufacturing process of a flame-retardant formaldehyde-free density board.

Background

The current wood board market mainly comprises plywood, ecological board, multi-layer board, particle board and density board, the plywood is artificial non-natural wood board, but the structure of the plywood is essentially different, especially the plywood, ecological board and multi-layer board, the plywood is formed by stacking and pressing massive or thick or thin solid wood boards, the density board is made of wood fiber or other plant fiber, the wood fiber or other plant fiber is used as raw material, the synthetic resin is applied, and the board pressed under the condition of heating and pressing is essentially different from the density board in structure. In contrast to density boards which are produced by pressing directly with fibers, but which are produced by making cellulose into chips or particles which are somewhat similar in structure, i.e. they are not pressed from a block of wood, wherein particle boards are particles made from wood or other lignocellulosic material, the main raw material is essentially irregular chips or particles, and the particles are glued under heat and pressure to form a wood-based board, as opposed to density boards which are pressed directly from fibers. Thus, the combination of properties of density board is between plywood, ecological board, multi-layer board and particle board.

As one of the most important home-made boards at present, the density boards themselves are basically made by the same process, i.e. wood or other plants are first made into fibers and then hot-pressed into corresponding boards. The existing density boards are only pure formaldehyde-free boards or pure flame-retardant boards, at present, no formaldehyde-free flame-retardant density boards exist in the market, formaldehyde-free boards (the formaldehyde-free boards are only artificial boards with extremely low relative formaldehyde content and absolutely no formaldehyde) exist, and boards with good flame retardant property are only the plywood, but the plywood has high cost and large wood consumption, and is neither economical nor applicable to a plurality of occasions such as decoration. The density board is easy to process secondarily, has stable size, can achieve excellent comprehensive performances of no formaldehyde, good flame retardance and high strength, can certainly realize a technical breakthrough in the field of artificial boards, and thoroughly changes the use pattern or even the whole industrial pattern in the field of the current decoration boards.

The density board with lower formaldehyde release amount or the density board with better strength on the market is prepared by fibers made of plant raw materials, the strength of the density board is far from insufficient, the requirements of both strength and flame retardance can not be met, when the wood fibers are prepared, a series of novel processes are prepared by adding a bi-component soybean meal adhesive, a phenol formaldehyde resin and a urea formaldehyde resin into the density board, and additionally adding a plurality of raw materials such as straws, modified soybean protein macromolecules, an antiseptic antibacterial agent, sand shrubs, methyl cellulose and the like, but the obtained density board is still difficult to release the flame retardance, the formaldehyde release amount and the strength, and needs to be improved urgently.

Disclosure of Invention

The invention aims to solve the technical problems and provides a manufacturing process of a flame-retardant formaldehyde-free density board, which can better solve the technical problems of poor internal bonding strength, poor formaldehyde release amount and poor flame retardance of the existing density board and can simultaneously improve the three-aspect performance of the internal bonding strength, the formaldehyde release amount and the flame retardance.

The technical scheme of the invention is as follows: a process for manufacturing a flame retardant formaldehyde-free density board, comprising the steps of:

(1) preparing wood into wood fibers at high temperature and high pressure;

(2) adding an adhesive, paraffin, a flame retardant and a dye into the wood fiber, and drying;

(3) the hot press solidifies and molds the mixed wood fiber;

in the step (1), the wood is poplar, the poplar is softened by steam and ground into the wood fiber by a hot grinding machine under the conditions that the temperature is 170-180 ℃, the cooking pressure is 9.5 +/-0.5 bar, and the cooking time is 3.5 +/-0.3 min, wherein the wood fiber comprises the following three dimensions and proportions thereof: 10-20% of wood fibers with the length of 2-5.4 mm and the length-width ratio of 63-110, 70-90% of wood fibers with the length of 0.125-2 mm and the length-width ratio of 35-63, and 20-35% of the rest wood fibers with the length of 0.06-0.125 mm;

in the step (2), the added adhesive is isocyanate, the flame retardant is a phosphorus flame retardant, and the various materials are added and mixed to meet the following requirements: isocyanate 40 +/-5 kg/m³5.5 +/-0.5 kg/m of paraffin wax³57 +/-4 kg/m of phosphorus series flame retardant³Dye 1.8 +/-0.6 kg/m³Drying the mixed material to ensure that the fiber moisture is 7 +/-0.5%;

in the step (3), the temperature of the hot press is 240 +/-5 ℃, 255 +/-5 ℃, 240 +/-5 ℃, 210 +/-5 ℃ and 140 +/-8 ℃ in sequence, and the corresponding duration is 25 +/-2 s, 21 +/-2 s, 23 +/-2 s, 28 +/-3 s and 35 +/-1 s in sequence; the pressures of the high-pressure area and the middle-pressure area of the hot press are respectively 4.5 +/-0.5N/mm²And 1. + -. 0.2N/mm². The residence time of the high-pressure area is not less than two thirds of the total hot pressing time, and the residence time is preferably 2/3-5/6 of the total hot pressing time of the hot press.

The invention has the beneficial effects that: the invention is based on the three-step method of the traditional process, the raw material selection of the traditional process (mainly directionally selecting poplar trees, if the rest wood is adopted, the density board with the same performance is difficult to obtain under the same condition) is improved on the component proportion and the process parameters, and the whole frame of the process is not changed, so the cost of technology upgrading is hardly changed, but the internal bonding strength, the formaldehyde release amount and the flame retardance of the density board prepared by the process are greatly improved compared with the existing density board, and the most critical effect is that the three comprehensive performances of the internal bonding strength, the formaldehyde release amount and the flame retardance are combined, and the three main excellent performances are integrated, which can not be easily achieved in the existing density board production and manufacturing technology, especially on the basis of not changing the frame of the traditional process, obtaining a density board with excellent comprehensive performance only in the cheap mode of changing the types of raw materials (specifying poplar trees), component ratios and process parameters is a huge breakthrough in the technology.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The invention will be further illustrated with reference to specific examples:

a manufacturing process of a flame-retardant formaldehyde-free density board mainly comprises the following steps: (1) preparing wood into wood fibers at high temperature and high pressure; (2) adding an adhesive, paraffin, a flame retardant and a dye into the wood fiber, and drying; (3) and solidifying and molding the mixed wood fiber by the hot press. In the step (1), the wood is poplar, the poplar is softened by steam and ground into the wood fiber by a hot grinding machine under the conditions that the temperature is 170-180 ℃, the cooking pressure is 9.5 +/-0.5 bar, and the cooking time is 3.5 +/-0.3 min, wherein the wood fiber comprises the following three dimensions and proportions thereof: the wood fiber with the length of 2 mm-5.4 mm and the length-width ratio of 63-110 accounts for 10% -20%, the wood fiber with the length of 0.125-2 mm and the length-width ratio of 35-63 accounts for 70% -90%, and the rest wood fiber with the length of 0.06-0.125 mm and the length-width ratio of 20-35.

In the step (2), the types of adhesives and flame retardants that can be selected at present are various, but here, the invention directionally selects and uses the added adhesives as isocyanate and the flame retardants as phosphorus flame retardants. After the materials are selected, the addition amount of the materials is required to meet the following requirements: isocyanate 40 +/-5 kg/m³5.5 +/-0.5 kg/m of paraffin wax³57 +/-4 kg/m of phosphorus series flame retardant³Dye 1.8 +/-0.6 kg/m³The mixed material is dried to make the fiber water content 7 plus or minus 0.5 percent. In the step (3), the temperature of the hot press is 240 ± 5 ℃, 255 ± 5 ℃, 240 ± 5 ℃, 210 ± 5 ℃ and 140 ± 8 ℃ in sequence, and the corresponding time duration is 25 ± 2s, 21 ± 2s, 23 ± 2s, 28 ± 3s and 35 ± 1s in sequence; the hot press passes through the high-pressure zone and the medium-pressure zone in sequence under the conditions of the temperature zones which change in sequence, wherein the pressure in the high-pressure zone and the medium-pressure zoneThe force is respectively 4.5 +/-0.5N/mm²And 1. + -. 0.2N/mm²The time can be distributed according to the sum of the time of the temperature areas, so that the high-pressure area stays for not less than two thirds of the total hot-pressing time, and the time preferably occupies 2/3-5/6 of the total hot-pressing time of the hot-pressing machine.

The proportions and process parameters of a plurality of groups of density boards prepared by the process method are given below, and those skilled in the art can prepare the density boards according to the material proportions and corresponding process parameters in the following table to obtain the flame-retardant formaldehyde-free board.

TABLE 1

The flame-retardant formaldehyde-free boards manufactured in the examples 1 to 8 in the table 1 are respectively tested for the internal bonding strength, the formaldehyde emission amount and the flame retardance, and the test results are shown in the following table; for comparative performance analysis, 8 kinds of available density boards on the market are randomly selected to perform three performance tests of internal bonding strength, formaldehyde emission and flame retardance under the same test conditions, and the statistics of the results are shown in the following table:

TABLE 2

In Table 2, it is to be noted that in the above test, the thickness of the density sheet produced by the present process and the thickness of the selected commercially available density sheet samples (sample plates A to H) were both 6 mm. The "strength" in the table refers to the internal bond strength of the density board, and the flame retardancy is tested by referring to GB/T20284 and GB/T8626 at an ignition time of 30s, and the explanation of the specific experimental data is for example 1, in the flame retardancy test data, the "97W/s" refers to the value of the burn growth rate index FIGRA0.2MJ of 97W/s; the term "short of the long wing edge" means that the flame transverse spreading degree of the density board does not reach the long wing edge of the sample in the combustion test of the density board; "5.9 MJ" means that the total heat release THR600s for 600s is 5.9 MJ; "132 mm" means that the flame tip height Fa is 132mm within 60s, and "no ignition" means that no combustion drips ignite the filter paper within 60 s.

As can be seen from the test data in Table 2, the density board manufactured by the method of the present invention has an internal bond strength of 2.2 to 2.6MPa and a formaldehyde emission of 0.01 to 0.016mg/m³Among flame retardant parameters, FIGRA0.2MJ is 97-118W/s, the flame transverse spreading degree does not reach the edge of the long wing of the sample except for the accident of the embodiment 8, THR600s is 5.9-7.9 MJ, the THR600s value of the embodiment 8 is higher than 7.5MJ, and the rest is in the range of 5.9-7.2 MJ, namely the THR600s of the density board in 6 embodiments is less than 7.5 MJ. The height Fa of the flame tip within 60s is 132-143 mm, i.e. less than 150 mm. Of the density boards produced in 8 examples, only example 2 was tested in which the combustion drips ignited the filter paper, and the rest were in a non-ignited safe state.

In a test of 8 randomly selected commercial density board samples under the same condition, the internal bonding strength value is 1.7-2.3 Mpa, compared with the internal bonding strength value of 2.2-2.6 Mpa of the density board provided by the invention, the strength is obviously low, and the internal bonding strength of only the sample plate F in the existing density boards is more than 2MPa to reach the level of the density board, and the rest is less than 2MPa, so that the strength of the density board provided by the invention is obviously superior to that of the existing density board. For the formaldehyde emission, the existing density boards are 0.015-0.052 mg/m³0.01-0.016 mg/m of the density board³The formaldehyde emission of (A) is much higher, much less than that of the density board of the invention, and only the formaldehyde emission of sample A (0.015 mg/m)³) It is marginally comparable to the density board of the present invention, however the internal bond strength is seen to be too low, at 1.7 MPa. Among the flame retardant parameters of the existing density boards, the flame growth rate index FIGRA0.2MJ is 127-165W/s, which is much higher than 97-118W/s of the density boards of the invention, and the existing density boards on the market show the phenomenon of extremely uneven distribution of the flame growth rate index, and most of the flame growth ratesThe indexes are all around 150W/s in practice, and the flame retardance is obviously poor. The flame transverse spreading degree of the existing density board except the sample board E spreads to the edge of the long wing, and the flame retardance of the existing density board is also proved to be inferior to that of the density board prepared by the invention. The THR600s of the existing density board is 7.9-10.3 MJ, while the THR600s of the density board is 5.9-7.9 MJ, and the difference between the THR600s and the MJ is large. The height Fa of the flame point in 60s of the existing density boards is 156-180 mm, which is larger than 132-143 mm of the density board, and the flame retardant property of the density board in 8 embodiments of the invention is better than that of the existing 8 density board samples; and of the density boards prepared in 8 examples, only example 2 was tested in which the burning drips ignited the filter paper, and the rest were all in a non-ignited safe state, reflecting the existing 8 density board samples, and only example 5 was not ignited.

In summary, the density boards of each embodiment prepared by the process provided by the present invention are superior to most existing density boards in terms of internal bonding strength, formaldehyde emission and flame retardancy, while the density boards prepared by the process provided by the present invention are significantly superior to existing density boards in view of overall performance, and although the internal bonding strength, formaldehyde emission and flame retardancy of individual boards are better, and even some of the performance of individual boards are comparable to those of the density boards of the present invention, the overall performance of the density boards is not satisfactory, for example, the sample board E in the existing density boards has better flame retardancy, but the formaldehyde emission and internal bonding strength are far inferior to those of the density boards of the present invention, while the internal bonding strength of the sample board F is as high as 2.3MPa, but the other performance is also poor, and it is difficult to achieve the internal bonding strength, The formaldehyde emission and the flame retardance are combined, and the reason for the excellent performance of a certain aspect of the density board is probably realized on the basis of sacrificing other performance parameters, however, the density board prepared by the process has the excellent combination property of combining the internal bonding strength, the formaldehyde emission and the flame retardance.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.