A high performance PBO paper and preparation method thereof

Abstract

The present invention discloses a high-performance PBO paper and a preparation method thereof, and belongs to the field of special paper preparation. PBO fiber filaments with a single fiber fineness of 1.5 to 3.0D are used as raw materials, and after pretreatment, they are cut into short fibers with a length of 3 to 6 mm and short fibers with a length of 0.8 to 1.6 mm; then, PBO pulp and PBO short fiber dispersion are prepared respectively, and the two are placed in a stirring tank with a volume ratio of 0.5 to 5:1, and the two are beaten to form a dispersion, and then put on the net, pressurized and formed at room temperature; and dried to obtain PBO paper. Among them, PBO fiber and / or pulp can effectively improve the hydrophilicity of the fiber surface, and the dispersant can effectively promote the dispersion of PBO fiber and / or pulp in water. Finally, the PBO paper prepared by the wet papermaking process has excellent mechanical properties and high temperature resistance.

Description

Technical Field

[0001] The invention specifically relates to a high-performance PBO paper and a preparation method thereof, and belongs to the field of special paper preparation. Background Art

[0002] Since the invention of paper, with the development of papermaking raw material sources, the use of paper has become more and more extensive. Especially in modern times, the development of various high-performance fibers has matured, and special paper made of high-performance fibers has further accelerated the development of the paper industry. Among them, aramid paper was developed earlier and the production process is relatively mature. It is generally used in national defense, military, aerospace, rail transportation, power electronics and other fields. Compared with aramid fiber, PBO fiber (poly(p-phenylene benzobisoxazole) fiber) has better mechanical properties, heat resistance and flame retardant properties. Therefore, paper made with PBO fiber as raw material has better performance and will have excellent dielectric properties, ablation resistance and other special properties.

[0003] At present, PBO fiber adopts liquid crystal spinning method. After the fiber is formed, it has good orientation and high molecular regularity, which makes the mechanical properties of PBO fiber particularly excellent. However, the surface polarity of PBO fiber is poor and the surface is smooth, resulting in insufficient bonding force between fibers, which makes the initial performance of PBO paper insufficient. In the production process of PBO paper, the main problems are that the fiber and pulp are not well dispersed in water, easy to agglomerate, uneven paper after forming, affecting the appearance; and after the paper is formed, the fiber bonding force is insufficient, the paper is not easy to be pulled continuously during the production process, and the paper strength is low.

[0004] The prior art "CN114790664A high-strength polyphenylene benzobisoxazole paper-based material" uses a PBO fiber precursor to prepare, then soaks the PBO base paper in the precursor solution, and uses the similarity between the PBO fiber and the precursor structure to increase the coating of the PBO fiber and the precursor, and then forms a PBO paper-based composite material after hot pressing and drying, so as to achieve the purpose of enhancing the performance of PBO paper. However, this method requires the preparation of a PBO precursor, the process is complicated, and a large amount of organic reagents are used as solvents. During the hot pressing and drying process, the organic solvents volatilize, causing environmental pollution and damaging the health of operators.

[0005] The paper-based material prepared by "CN112726283A A poly(p-phenylene benzobisoxazole) fiber paper-based material for high-temperature resistant honeycomb core material and its preparation method" has the characteristics of good high-temperature resistance and high mechanical strength, which can solve the problems of low internal bonding strength of existing PBO fiber-reinforced composite materials and poor performance stability of composite materials under high temperature conditions (300°C). However, it uses aramid precipitated pulp as an adhesive. However, the temperature resistance of aramid is lower than that of PBO fiber, and the overall temperature resistance of paper will be lower than that of pure PBO paper. In addition, the preparation process of aramid precipitated pulp is more complicated, resulting in an increase in the cost of paper.

[0006] "CN1683712 PBO fiber paper-based material and its preparation method and application" aims to provide PBO fiber paper-based material and paper-based composite materials mainly composed of PBO fibers. However, due to the smooth surface of PBO fibers, poor bonding between untreated PBO fibers, and poor affinity between PBO fibers and resins, this method requires a more complex process to solve the fiber bonding problem. Summary of the invention

[0007] The present invention aims to solve the problems faced by PBO fibers and pulp in the prior art in the process of preparing PBO paper, such as uneven dispersion of fibers or / and pulp in aqueous solution, insufficient hydrophilicity, and ultimately affecting the comprehensive performance of PBO paper. In this technical solution, PBO fibers or / and pulp can effectively improve the hydrophilicity of the fiber surface, and the dispersant can effectively promote the dispersion of PBO fibers or / and pulp in water. Finally, the PBO paper prepared by the wet papermaking process has excellent mechanical properties and high temperature resistance.

[0008] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0009] The first purpose of the technical scheme is to propose: a high-performance PBO paper, which uses PBO fiber filaments with a single fiber fineness of 1.5 to 3.0D as raw materials, and after pretreatment, cuts into short fibers with a length of 3 to 6 mm and short fibers with a length of 0.8 to 1.6 mm; then, prepares PBO pulp and PBO short fiber dispersion respectively, mixes, beats, shapes the dispersion; puts on the net, presses and forms; and dries to obtain;

[0010] The finished product indicators of the high-performance PBO paper include: tear index ≥ 9.07 mN·m 2 ·g -1 , tensile energy absorption ≥3.4 J·m -2 , tensile strength ≥7.6MPa, elongation at break ≤1.0%.

[0011] The second purpose of the technical solution is to propose: a method for preparing high-performance PBO paper, comprising the following steps:

[0012] 1) Preprocessing

[0013] Using PBO fiber filaments with a single fiber fineness of 1.5-3.0D as raw materials, at 400-600°C, with a stretching ratio of 1.00-1.02, processing for 5-30s, and winding for use;

[0014] The pretreatment of the PBO fiber is mainly to achieve: increase the surface activity of the PBO fiber, improve the cohesion between the fibers, and improve the dispersibility of the fibers in the solution, so as to facilitate the subsequent preparation of PBO pulp and improve the mechanical properties of the subsequent finished paper, that is, to ensure the preparation efficiency and quality of the subsequent processes.

[0015] Among them, the raw material is selected as "PBO fiber filament with a single fiber fineness of 1.5 to 3.0D". If the fineness is lower than 1.5D, it is easy to break during pretreatment, affecting the yield rate; if the fineness is higher than 3.0D, it is not easy to be fully activated during pretreatment, affecting the subsequent paper forming, and reducing the performance of the paper;

[0016] The treatment is carried out at 400-600℃, which can complete the fiber activation on the basis of ensuring the mechanical properties of PBO fiber. If it is higher than 600℃, the fiber will be severely damaged and paper will not be easy to form; if it is lower than 400℃, the purpose of fiber pretreatment cannot be achieved;

[0017] The stretching ratio is 1.00-1.02, which can better ensure that there will be no significant changes in the performance of the PBO fiber during the continuous pretreatment process, that is, the fiber will not shrink during the pretreatment process. Therefore, the minimum stretching ratio is 1.0. If the stretching ratio is greater than 1.02, it will affect the mechanical properties of the fiber.

[0018] The treatment time is 5 to 30 seconds, which ensures that the PBO fiber can achieve the pretreatment purpose without affecting the fiber performance due to too long treatment time. For example, if the treatment time is less than 5 seconds, the fiber pretreatment is insufficient and the subsequent purpose cannot be achieved; if the treatment time is more than 30 seconds, the fiber performance is seriously damaged, which seriously affects the subsequent paper forming and paper performance.

[0019] 2) Preparation of chopped fibers and short fibers

[0020] The pretreated PBO fibers were cut into two different specifications: short fibers with a length of 0.8 to 1.6 mm and short chopped fibers with a length of 3 to 6 mm;

[0021] The reason why the length of the chopped fibers is limited to 3 to 6 mm is to facilitate dispersion in the subsequent dispersion process. Longer chopped fibers are not easy to disperse; shorter chopped fibers have lower mechanical properties after paper forming. Therefore, after considering various factors, the length of the chopped fibers is limited to 3 to 6 mm.

[0022] The length of the short fibers is limited to 0.8 to 1.6 mm in order to make them easier to swell and disperse in the subsequent pulp preparation process;

[0023] 3) Preparation of PBO pulp

[0024] The short fibers treated in step 2) are placed in a stirring tank with a ratio of the short fiber mass to the treatment agent solution volume of 1:10 to 100, and then the treatment agent solution is added and stirred at room temperature for 5 to 60 minutes;

[0025] The treatment agent solution is a mixture of 5-30% sulfuric acid and 0.05-2% potassium permanganate, or a 5-30% nitric acid solution.

[0026] In this treatment process, the mass of short fibers and the treatment agent solution are mixed at a volume ratio of 1:10 to 100. This limitation can not only fully disperse the short fibers, but also ensure the effective use of the treatment agent and effectively reduce costs. The treatment is stirred at room temperature for 5 to 60 minutes. The "normal temperature" involved has the general meaning in this field, generally referring to a temperature of 15-28°C. The limitation of this treatment time can fully treat the fibers without reducing production efficiency due to too long a time, and too long a time will also damage the fibers. In addition, when the short fibers are in the treatment agent solution, the treatment agent destroys the connection between the fibers, fibrillates the fibers, breaks the fibers into smaller pieces, and roughens the fiber surface, which can achieve better bonding in the subsequent papermaking process and improve the mechanical properties of the paper. The selection of this concentration of treatment agent can ensure the formation of PBO pulp and avoid excessive damage to the fibers.

[0027] Wash with pure water until neutral, filter, and dry; add water to prepare an aqueous solution with a PBO fiber concentration of 0.2-10%. The fibers within this concentration can be better dispersed. For example, if the concentration is too high, the fibers will agglomerate, and if the concentration is too low, the paper forming will be affected. Then, add a dispersant and control the dispersant concentration to 0.5-1.0% (the control of this concentration effectively assists the fiber dispersion and ensures that the dispersant can be better dissolved, thereby improving the utilization rate of the dispersant. For example, if the concentration is less than this, the fiber dispersion cannot be assisted; if the concentration is greater than this, the dispersant is difficult to dissolve and the cost is too high). Beat in a pulping machine at 2000-4000r / min for 5-10 minutes to make PBO pulp;

[0028] Wherein, the dispersant is one of hydroxyethyl cellulose, sodium lignin sulfonate, maleic acid-acrylic acid copolymer, polyoxyethylene ether and nonionic polyacrylamide, or a mixture of any two or more thereof;

[0029] "The beater runs at 2000-4000r / min for 5-10 minutes" to ensure that the pulp is dispersed more evenly and better bonded to the paper for subsequent forming. The dispersant adheres to the short fibers, increases the polarity of the fiber surface, enhances the hydrophilicity, makes it easier for water molecules to wrap around a single fiber, weakens the adsorption between fibers, and thus improves the dispersion of the fibers in water. The fibers are evenly dispersed, and after forming, the paper has a better appearance and more stable performance.

[0030] 4) Preparation of PBO chopped fiber dispersion

[0031] Add pure water to the chopped fibers to prepare an aqueous solution with a PBO fiber concentration of 0.2-10%. The fibers within this concentration can be better dispersed. For example, if the concentration is too high, the fibers will agglomerate, and if the concentration is too low, the paper forming will be affected. Then, add a dispersant to control the concentration of the dispersant to 0.5-1.0% (similarly, the control of this concentration effectively assists the fiber dispersion and ensures that the dispersant can be better dissolved, thereby improving the utilization rate of the dispersant. For example, if the concentration is less than this, the fiber dispersion cannot be assisted; if the concentration is greater than this, the dispersant is difficult to dissolve and the cost is high). The fibers are beaten in a beater at 2000-4000 r / min for 0.5-5 minutes to prepare a PBO chopped fiber dispersion.

[0032] Wherein, the dispersant is one of hydroxyethyl cellulose, sodium lignin sulfonate, maleic acid-acrylic acid copolymer, polyoxyethylene ether and nonionic polyacrylamide, or a mixture of any two or more thereof;

[0033] "The beater runs at 2000-4000r / min for 5-10 minutes" to ensure that the pulp is dispersed more evenly and better bonded to the paper for subsequent forming. The dispersant adheres to the chopped fibers, increases the polarity of the fiber surface, enhances the hydrophilicity, makes it easier for water molecules to wrap around a single fiber, weakens the adsorption between fibers, and thus improves the dispersion of the fibers in water. The fibers are evenly dispersed, and after forming, the paper has a better appearance and more stable performance.

[0034] 5) Preparation of PBO paper

[0035] The PBO pulp obtained in step 3) and the PBO chopped fiber dispersion obtained in step 4) are placed in a stirring tank at a volume ratio of 0.5 to 5:1, and are beaten in a beater at 2000 to 4000 r / min for 0.5 to 2 minutes to form a uniform dispersion, and then, are put on a net, press-formed at room temperature, and dried to obtain PBO paper;

[0036] The volume ratio of the PBO pulp to the PBO chopped fiber dispersion is 0.5 to 5:1, which ensures the proper ratio of the PBO pulp to the PBO chopped fibers in the paper, and at this ratio, the performance of the paper is also guaranteed.

[0037] "Pulp at 2000-4000r / min for 0.5-2min" to fully disperse the PBO pulp and PBO chopped fibers to ensure uniform paper with high performance. If the dispersion is uneven during this process, the paper will not be easy to form, or the formed paper will have uneven appearance and poor performance.

[0038] The beneficial technical effects brought about by adopting this technical solution are:

[0039] In the present invention, by specially controlling each process and corresponding conditions, it is not only ensured that PBO paper with high performance (such as mechanical properties and high temperature resistance) is prepared, but also the controllability, stability and smoothness of the preparation process are achieved. At the same time, the problems faced by PBO fibers and pulp in the prior art in the preparation of PBO paper, such as uneven dispersion of fibers or / and pulp in aqueous solution and insufficient hydrophilicity, which ultimately affect the comprehensive performance of PBO paper, are solved;

[0040] In addition, no organic solvent is needed to clean the fiber surface, effectively avoiding environmental problems. In addition, fewer types of reagents are used, which reduces the operation process and is simple and easy to operate. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment provides: a high-performance PBO paper, which uses PBO fiber filaments with a single fiber fineness of 1.5 to 3.0D as raw materials, and after pretreatment, cuts into short fibers with a length of 3 to 6 mm and short fibers with a length of 0.8 to 1.6 mm; then, prepares PBO pulp and PBO short fiber dispersion respectively, mixes, beats, shapes the dispersion; puts on a net, presses and shapes; and dries to obtain the paper;

[0044] The finished product indicators of the high-performance PBO paper include: tear index ≥ 9.07 mN·m 2 ·g -1 , tensile energy absorption ≥3.4 J·m -2 , tensile strength ≥7.6MPa, elongation at break ≤1.0%.

[0045] Example 2

[0046] This embodiment provides: a method for preparing high-performance PBO paper, comprising the following steps:

[0047] 1) Pretreatment of PBO fiber: PBO fiber filament with a single fiber fineness of 1.5D was treated at 535°C, with a stretching ratio of 1.006, for 12 seconds, and then rolled up for use;

[0048] 2) Preparation of PBO short fibers and PBO chopped fibers: The pretreated PBO fibers were cut into two different specifications: one was 3 mm short fibers and the other was 6 mm chopped fibers;

[0049] 3) Preparation of PBO pulp: according to the ratio of the mass of short fibers to the volume of the treatment agent solution of 1:10, a certain amount of short fibers were weighed and placed in a stirring tank, then a certain amount of the treatment agent solution was added, stirred at room temperature for 45 minutes, washed with pure water until neutral, filtered, dried, and then added with pure water to prepare an aqueous solution with a PBO fiber concentration of 5%;

[0050] Adding a dispersant to the PBO fiber solution, controlling the concentration of the dispersant to be 0.5%, beating the solution in a pulping machine at 3600 r / min for 8 minutes to prepare PBO pulp;

[0051] The preparation of the treatment agent is a mixture of 10% sulfuric acid and 0.5% potassium permanganate; the dispersant is hydroxyethyl cellulose;

[0052] 4) Preparation of PBO chopped fiber dispersion: Weigh a certain amount of PBO chopped fibers, place them in a stirring tank, add an appropriate amount of pure water, and prepare an aqueous solution with a PBO fiber concentration of 5%; add a dispersant, control the dispersant concentration to 0.5%, and beat in a beater at 3600r / min for 3min to prepare a PBO chopped fiber dispersion;

[0053] Among them, the dispersant type is hydroxyethyl cellulose;

[0054] 5) Preparation of PBO paper: Take a certain amount of PBO pulp solution and PBO chopped fiber dispersion at a volume ratio of 0.8:1, place them in a stirring tank, and then use a pulper at 4000r / min for 1min to form a uniform dispersion. Then, put it on the net to form, press it at room temperature for a certain period of time and then dry it to obtain PBO paper.

[0055] The obtained PBO paper was subjected to performance tests, and the results are shown in Table 1 below.

[0056]

[0057] Discussion Example 1

[0058] This discussion example discusses the effects of PBO fiber pretreatment, chopped fiber length, short fiber length and PBO pulp preparation on PBO fiber properties or PBO paper properties, and further illustrates the present invention.

[0059] 1. Effect of PBO fiber pretreatment on PBO fiber properties

[0060] On the basis of Example 2, the fineness, processing temperature, drawing ratio and processing time in Table 2 below are set respectively, and then the PBO fiber is pretreated; finally, the performance of the pretreated PBO fiber is tested, and the results are shown in Table 2 below.

[0061]

[0062] It can be seen that: selecting the appropriate PBO fiber pretreatment process can ensure the high strength and high modulus of the fiber as much as possible during fiber pretreatment, so that the performance of the formed paper is better. Based on this, considering the performance, cost, energy consumption, efficiency, etc. of the pretreated PBO fiber, the process of "using PBO fiber filaments with a single fiber fineness of 1.5-3.0D as raw material, at 400-600℃, with a stretching ratio of 1.00-1.02, and treating for 5-30s" is selected.

[0063] 2. Effect of Short Cut Fiber Length on PBO Paper Properties

[0064] PBO fibers with a fineness of 1.5D were selected, the stretching ratio was maintained at 1.006, and the fibers were treated at 535°C for 12s to obtain pretreated PBO fibers; then, the fibers were cut into short fiber lengths as shown in Table 3, and PBO paper was prepared based on Example 2; finally, the performance of the PBO paper was tested, and the results are shown in Table 3.

[0065]

[0066] It can be seen that short-cut fibers are the skeleton material in paper. If the length of short-cut fibers is too short, they cannot effectively provide the tensile properties of paper. The tensile strength of paper made from 3mm short-cut fibers is relatively low; 9mm short-cut fibers are not easy to disperse, which will also cause insufficient tensile properties of paper; 6mm short-cut fibers can be effectively dispersed and can also ensure the tensile strength of paper. Therefore, considering the performance of PBO paper (tensile strength), cost, efficiency, etc., "short-cut fibers with a length of 3 to 6mm" are selected.

[0067] 3. Effect of short fiber length on PBO paper properties

[0068] PBO fibers with a fineness of 1.5D were selected, the stretching ratio was maintained at 1.006, and the fibers were treated at 535°C for 12s to obtain pretreated PBO fibers; then, the fibers were cut into short fiber lengths as shown in Table 4, and PBO paper was prepared based on Example 2; finally, the performance of the PBO paper was tested, and the results are shown in Table 4.

[0069]

[0070] It can be seen that PBO short fibers are processed to make PBO pulp, which is the adhesive of PBO paper. Therefore, the length of short fibers also has a great influence on the tensile strength of paper. If the short fibers are too short, the size of the pulp will be too small, which is not conducive to the cohesion with the short-cut fibers; if the short fibers are too long, it will be not conducive to the penetration of the treatment agent. Therefore, considering the performance of PBO paper (tensile strength), cost, efficiency, etc., "short fibers with a length of 0.8 to 1.6 mm" are selected.

[0071] 4. Effect of PBO pulp preparation on PBO paper properties

[0072] PBO fibers with a fineness of 1.5D were selected, the stretching ratio was maintained at 1.006, and the fibers were treated at 535°C for 12s to obtain pretreated PBO fibers; the fibers were cut into short fibers with a length of 1.2mm, and then the mass volume ratio, treatment agent concentration and treatment time in Table 5 were set to prepare PBO pulp; and PBO paper was prepared based on Example 2; finally, the performance of the PBO paper was tested, and the results are shown in Table 5.

[0073]

[0074] It can be seen that PBO pulp prepared after short fiber treatment, as a binder for PBO paper, is an important component of PBO paper. The specific surface area of ​​PBO pulp is an important indicator for measuring pulp performance. The larger the specific surface area, the better the surface performance of the pulp, the more capillary fibers, and the better the adhesion in the paper.

[0075] Discussion Example 2

[0076] This discussion example further discusses the effect of dispersant concentration on PBO fibers to further illustrate the present invention.

[0077] The PBO fiber aqueous solution was treated with dispersants of concentrations shown in Table 6 below. The results are shown in Table 6 below.

[0078]

[0079] Discussion Example 3

[0080] In this discussion example, the performance of other PBO fiber paper samples was compared with the PBO fiber paper prepared in Example 2. The results are shown in Table 7.

[0081]

Claims

1. A method for preparing high-performance PBO paper, characterized in that: The steps include: 1) Preprocessing Using PBO fiber filaments with a single fiber fineness of 1.5-3.0D as raw materials, at 400-600°C, with a stretching ratio of 1.00-1.02, processing for 5-30s, winding and setting aside; 2) Preparation of chopped fibers and short fibers The pretreated PBO fibers were cut into two different specifications: short fibers with a length of 0.8 to 1.6 mm and short chopped fibers with a length of 3 to 6 mm; 3) Preparation of PBO pulp The treatment agent solution is added to the short fibers at a ratio of 1:10 to 100 in volume to the treatment agent solution; the fibers are then washed with pure water until neutral, filtered, and dried; Add pure water to prepare an aqueous solution with a PBO fiber concentration of 0.2-10%, add a dispersant, control the dispersant concentration to 0.5-1.0%, and beat to prepare PBO pulp; 4) Preparation of PBO chopped fiber dispersion Adding pure water to the chopped fibers to prepare an aqueous solution with a PBO fiber concentration of 0.2 to 10%; then, adding a dispersant to control the dispersant concentration to 0.5 to 1.0%, beating the fibers to prepare a PBO chopped fiber dispersion; 5) Preparation of PBO paper The PBO pulp obtained in step 3) and the PBO chopped fiber dispersion obtained in step 4) are mixed at a volume ratio of 0.5 to 5:1, and the mixture is beaten, placed on a screen, and pressurized to form; After drying, PBO paper is obtained.

2. The method for preparing high-performance PBO paper according to claim 1, characterized in that: The finished product indicators of the high-performance PBO paper include: tear index ≥ 9.07 mN·m 2 ·g -1 , tensile energy absorption ≥3.4 J·m -2 , tensile strength ≥7.6MPa, elongation at break ≤1.0%.

3. The method for preparing high-performance PBO paper according to claim 1, characterized in that: In step 3), the treatment agent solution is a mixed solution of 5-30% sulfuric acid and 0.05-2% potassium permanganate; or, the treatment agent solution is a 5-30% nitric acid solution.

4. The method for preparing high-performance PBO paper according to claim 1, characterized in that: In step 3), stirring is performed at room temperature for 5 to 60 minutes.

5. The method for preparing high-performance PBO paper according to claim 1, characterized in that: In steps 3) and 4), the dispersant is one of hydroxyethyl cellulose, sodium lignin sulfonate, maleic acid-acrylic acid copolymer, polyoxyethylene ether and non-ionic polyacrylamide, or a mixture of any two or more thereof.

6. The method for preparing high-performance PBO paper according to claim 1, characterized in that: In steps 3) to 5), a beater is used at 2000 to 4000 r / min for 5 to 10 minutes.

7. The method for preparing high-performance PBO paper according to claim 1, characterized in that: In step 5), pressure molding is performed at room temperature.

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