Polyphenylene sulfide fiber composite insulation paper and preparation process thereof

Abstract

The invention relates to the technical crossing field of polyphenylene sulfide fiber paper, special papermaking and insulation paper, in particular to high-temperature-resistant polyphenylene sulfide fiber composite insulation paper and a preparation process thereof. The high-temperature-resistant polyphenylene sulfide fiber composite insulation paper with a dense structure similar to reinforcing steel bar-mortar is prepared by preferably selecting the polyphenylene sulfide fiber with higher cost performance as a raw material and taking the aramid fibrid as a filling agent and an adhesive and adopting a wet papermaking process. The prepared composite paper has excellent temperature resistance and chemical corrosion resistance, the production process flow is short, the production process is free of pollution, the industrial production cost of the composite paper can be reduced, the temperature resistance and chemical stability of medium-and-low-end application insulation paper are improved, the application field of the composite paper in a more severe environment is widened, and the composite paper has good application prospects. Good economic benefits and application values are realized.

Description

Technical Field

[0001] The invention relates to the cross-field of polyphenylene sulfide fiber paper, special papermaking and insulating paper technology, and in particular to polyphenylene sulfide fiber composite insulating paper and a preparation process thereof. Background Art

[0002] As a key basic material for pad insulation, turn-to-turn insulation, phase-to-phase insulation and slot insulation of large electrical equipment, insulating paper ensures the long-term and safe operation of large electrical equipment. At present, the most widely used in the field of electrical insulation is aramid insulating paper made of aramid chopped fibers, aramid precipitated fibers or pulp fibers. However, due to the high cost of aramid fibers and their smooth, hydrophobic and inert surfaces, the interface bonding of traditional aramid insulating paper is weak, the production cost is high, and it is difficult to meet the application needs in the field of medium and low-grade insulation.

[0003] As a high-performance engineering plastic, polyphenylene sulfide (PPS) has shown unique advantages in the field of insulating materials. Polyphenylene sulfide has excellent high temperature resistance, chemical corrosion resistance, flame retardancy, insulation and excellent mechanical properties. It can work stably for a long time at a temperature of up to 200-220°C, and can resist the corrosion of various acids, alkalis and organic solvents. Its chemical stability is similar to that of the "king of plastics" polytetrafluoroethylene (PTFE). At the same time, due to its high sulfur content, PPS also has excellent flame retardant properties, with a limiting oxygen index of up to 34%. It will not drip when burning and will extinguish itself when away from the fire. In terms of electrical insulation, PPS has excellent electrical insulation properties, small dielectric constant, low dielectric loss, and high dielectric strength. It is an excellent electrical insulation material. In addition, the production cost of polyphenylene sulfide fiber is much lower than that of aramid fiber, and it is expected to become the best insulation material in the mid- and low-end markets.

[0004] However, polyphenylene sulfide fiber is not easy to form by wet method, has poor temperature resistance and is prone to shrinkage when heated, which causes dimensional instability in insulation applications and affects further applications. Summary of the invention

[0005] In view of the problems that polyphenylene sulfide fiber paper is difficult to form by wet method, has poor temperature resistance stability, and is easily shrunk when heated, resulting in unstable size of the insulating paper, the present invention provides a high-temperature resistant polyphenylene sulfide fiber composite insulating paper and a preparation process thereof.

[0006] The present invention is achieved through the following technical solutions: A high temperature resistant polyphenylene sulfide fiber composite insulating paper and a preparation process thereof, comprising the following steps: S1, using polyethylene oxide solution as a dispersant and water to decompose polyphenylene sulfide fiber, meta-aramid fibrid and para-aramid pulp fiber to obtain mixed fiber A; S2, forming a wet paper web B from the mixed fiber A by a wet forming process; S3, the wet paper web B is subjected to cold pressing treatment, vacuum drying treatment and hot pressing treatment in sequence to obtain a high temperature resistant polyphenylene sulfide fiber composite insulating paper C.

[0007] Preferably, in S1, the length of the polyphenylene sulfide fiber is 3-6 mm, the diameter is 0.75-0.89 dtex, the average fiber length of the meta-aramid fiber is 0.6-1.0 mm, the degree of fibrillation is 45-55° SR, and the specific surface area is 8-12 m 2 / g; the average fiber length of para-aramid pulp fiber is 0.9-1.3mm, the degree of fibrillation is 40-48°SR, and the specific surface area is 7.5-10m 2 / g.

[0008] Preferably, in S1, the mass ratio of polyphenylene sulfide fiber, aramid fibrid and aramid pulp fiber is (40-60) wt%: (34-50) wt%: (6-10) wt%.

[0009] Preferably, in S1, the dispersant is a polyethylene oxide solution with a concentration of 0.1 wt%-1 wt%.

[0010] Preferably, in S1, the ratio of polyphenylene sulfide fiber, aramid fiber, aramid pulp fiber, dispersant and deionized water is (1.0048-1.5072) g: (0.8541-1.2560) g: (0.1507-0.2512) g: (10-20) mL: (0.8-1.2) L.

[0011] Preferably, in S2, the parameters of the wet forming process are: dehydration time is 5-10s, and vacuum suction pressure is 1-5MPa.

[0012] Preferably, in S3, the pressure during the cold pressing treatment is 5-10 MPa, and the pressing time is 5-8 min.

[0013] Preferably, in S3, the vacuum drying process is carried out at a temperature of 100-105° C. and a drying time of 10-15 min.

[0014] Preferably, in S3, the pressure during the hot pressing treatment is 13-15 MPa, the temperature is 180-200° C., and the time is 12-20 min.

[0015] A high-temperature resistant polyphenylene sulfide fiber composite insulating paper prepared by the high-temperature resistant polyphenylene sulfide fiber composite insulating paper preparation process.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a high-temperature resistant polyphenylene sulfide fiber composite insulating paper and a preparation process thereof. The high-temperature resistant polyphenylene sulfide fiber composite insulating paper has high dielectric strength, low dielectric constant and dielectric loss and has the advantages of moderate raw material price, convenient processing process and the like while ensuring excellent dielectric properties, mechanical properties and high-temperature resistance of the paper-based material.

[0017] Specifically, meta-aramid fibrils are introduced as auxiliary fibers, fillers and adhesives. On the one hand, aramid fibrils have good water dispersion properties, which can assist the uniform dispersion of polyphenylene sulfide fibers, prepare high-quality slurry and improve the uniformity of paper. On the other hand, the aramid fibrils have rich amino and carboxyl groups at the interface, which promote stress transfer between fibers after being evenly and tightly interwoven with polyphenylene sulfide fibers, forming a dense structure similar to "rebar-mortar", thereby improving the mechanical strength of the composite paper.

[0018] Para-aramid pulp is introduced as reinforcing fiber and heat-stabilizing fiber. On the one hand, para-aramid fiber has higher modulus and strength, which helps to improve the mechanical properties of paper. On the other hand, aramid pulp has rich fiber tentacles, which is conducive to further interweaving to form a dense structure and improve the insulation and dielectric properties of paper.

[0019] Furthermore, the present invention uses polyphenylene sulfide fiber, which is more cost-effective and has excellent temperature resistance grade on the market, as raw material, which improves the temperature resistance and chemical stability of the insulating paper and broadens the application scenarios under complex environmental conditions.

[0020] Furthermore, the drying process of the present invention has been optimized for a long time, and the preferred drying temperature is 100°C-105°C. In this temperature range, the paper fiber can be dried and dehydrated with maximum efficiency, while on the other hand, excessive energy consumption can be avoided and production safety can be achieved.

[0021] Furthermore, the present invention optimizes the high-temperature hot pressing process to soften the polyphenylene sulfide fibers and bond them to each other. The optimization of the process is based on the physical and chemical properties of aramid fibers and polyphenylene sulfide fibers, which softens the fibers to increase the bonding strength and reduce the porosity of the paper without causing the fibers to become parchment-like and age-ineffective.

[0022] Furthermore, the reagents used in the present invention are all conventional pharmaceutical reagents, which are low-toxic, cheap, and easily available, and the equipment used are all conventional instruments and equipment, which lays a foundation for the industrial production of high-temperature resistant polyphenylene sulfide fiber composite insulation paper and improves the feasibility of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1The process of preparing a high temperature resistant polyphenylene sulfide fiber composite insulation paper of the present invention is shown in the figure; Figure 2 This is a surface SEM image of the composite paper prepared in Example 1; Figure 3 This is a cross-sectional SEM image of the composite paper prepared in Example 1; Figure 4 The dielectric constant variation trend diagram of the composite paper prepared in Examples 1 to 5 at different frequencies; Figure 5 The dielectric loss variation trend diagram of the composite paper prepared in Examples 1 to 5 at different frequencies; Figure 6 The tensile strength characterization diagram of the composite paper prepared in Examples 1 to 5; Figure 7 The dielectric strength characterization diagram of the composite paper prepared in Examples 1 to 5; Figure 8 The limiting oxygen index characterization diagram of the composite paper prepared in Examples 1 to 5; Fig. 9 TG curves of the composite papers prepared in Examples 1 to 5; Fig.10 DTG curves of the composite papers prepared in Examples 1 to 5; DETAILED DESCRIPTION The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0024] The invention discloses a high temperature resistant polyphenylene sulfide fiber composite insulating paper and a preparation process thereof, comprising the following steps: S1, placing a certain proportion of polyphenylene sulfide fiber and aramid fibrid in a fiber disintegrator, adding a dispersant and deionized water, and fully disintegrating to obtain mixed fiber A; Among them, the length of polyphenylene sulfide fiber is 3-6mm, the fineness is 0.75-0.89dtex; the average fiber length of meta-aramid fiber is 0.6-1.0mm, the degree of fibrillation is 45-55°SR, and the specific surface area is 8-12m 2 / g; the average fiber length of para-aramid pulp fiber is 0.9-1.3mm, the degree of fibrillation is 40-48°SR, and the specific surface area is 7.5-10m 2 / g. The mass ratio of polyphenylene sulfide fiber, aramid fibrid and aramid pulp fiber is (40-60) wt%: (35-55) wt%: (5-10) wt%.

[0025] The ratio of polyphenylene sulfide fiber, aramid fiber, aramid pulp fiber, dispersant and deionized water is (1.0048-1.5072) g: (0.8541-1.2560) g: (0.1507-0.2512) g: (10-20) mL: (0.8-1.2) L. The dispersant is a polyethylene oxide solution with a concentration of 0.1wt%-1wt%.

[0026] During dispersion, the dispersion speed is (20000~40000) revolutions, which is used to give the best dispersion process range, not limited to this parameter.

[0027] S2, using a wet forming process, the mixed fiber A and deionized water are mixed in a ratio of (0.8-1.2) L: (7-9) L on a standard sheeter to form a wet paper web B. The function of adding deionized water is to fully dilute and disperse the fibers. The amount of deionized water added is not limited under this parameter. The parameters of the wet forming process are: dehydration time is 5-10s, and vacuum suction pressure is 1-5MPa.

[0028] S3, the wet paper web B is subjected to cold pressing, vacuum drying and hot pressing in sequence to obtain high temperature resistant polyphenylene sulfide fiber composite insulation paper C. During the cold pressing, the pressure is 5-10 MPa and the pressing time is 5-8 min. During the vacuum drying, the temperature is 100-105°C and the drying time is 10-15 min. During the hot pressing, the pressure is 13-15 MPa, the temperature is 180-200°C and the time is 12-20 min.

[0029] The invention discloses a high temperature resistant polyphenylene sulfide fiber composite paper, and the process has low power consumption, is easy to obtain, and is highly efficient, and has good social and economic benefits and application value.

[0030] Example 1 S1, 1.5072 g of polyphenylene sulfide fiber, 0.8541 g of aramid fibrid, and 0.1507 g of aramid pulp fiber were placed in a fiber disintegrator, 10 ml of 1 wt% polyethylene oxide solution and 0.8 L of deionized water were added, and the mixture was fully disintegrated for 20,000 revolutions to obtain mixed fiber A; S2, using a wet forming process to prepare a wet paper web B by mixing mixed fiber A and deionized water in a ratio of 0.8L:9L on a standard paper machine; S3, the wet paper web B is first cold pressed at 5 MPa for 5 min, then vacuum dried at 105°C for 10 min, and finally hot pressed at 13 MPa and 200°C for 15 min to obtain a high temperature resistant polyphenylene sulfide fiber composite insulation paper product C.

[0031] The high temperature resistant polyphenylene sulfide fiber composite insulation paper product C obtained in Example 1 has excellent dielectric properties, a thickness of 0.111 mm, a mechanical strength of 35.7 N / cm, a dielectric strength of 4.37 kV / mm, and a dielectric constant of only 0.03 (10 4 Hz).

[0032] Example 2 S1, 1.3816 g of polyphenylene sulfide fiber, 0.9546 g of aramid fibrid, and 0.1758 g of aramid pulp fiber were placed in a fiber disintegrator, 11 ml of 1 wt% polyethylene oxide solution and 0.9 L of deionized water were added, and the mixture was fully disintegrated for 40,000 revolutions to obtain mixed fiber A; S2, using a wet forming process to prepare a wet paper web B by mixing mixed fiber A and deionized water in a ratio of 0.9L:8.5L on a standard paper machine; S3, the wet paper web B is first cold pressed at 6 MPa for 5 min, then vacuum dried at 104°C for 10 min, and finally hot pressed at 12 MPa and 200°C for 14 min to obtain a high temperature resistant polyphenylene sulfide fiber composite insulation paper product C.

[0033] The dielectric properties of the high temperature resistant polyphenylene sulfide fiber composite insulation paper product C obtained in Example 2 are as follows: the thickness is 0.132 mm, the mechanical strength can reach 30.3 N / cm, the dielectric strength can reach 3.84 kV / mm, and the dielectric constant is only 0.01 (10 4 Hz).

[0034] Example 3 S1, 1.2560 g of polyphenylene sulfide fiber, 1.0550 g of aramid fibrid, and 0.2010 g of aramid pulp fiber were placed in a fiber disintegrator, 12 ml of 1 wt% polyethylene oxide solution and 1 L of deionized water were added, and the mixture was fully disintegrated for 25,000 revolutions to obtain mixed fiber A; S2, using a wet forming process to prepare a wet paper web B by mixing mixed fiber A and deionized water in a ratio of 1L:8L on a standard paper machine; S3, the wet paper web B is first cold pressed at 7 MPa for 5 min, then vacuum dried at 103°C for 10 min, and finally hot pressed at 13 MPa and 200°C for 13 min to obtain a high temperature resistant polyphenylene sulfide fiber composite insulation paper product C.

[0035] The dielectric properties of the high temperature resistant polyphenylene sulfide fiber composite insulation paper product C obtained in Example 3 are as follows: the thickness is 0.132 mm, the mechanical strength can reach 20.5 N / cm, the dielectric strength can reach 3.06 kV / mm, and the dielectric constant is only 0.02 (10 4 Hz).

[0036] Example 4 S1, 1.1304 g of polyphenylene sulfide fiber, 1.1555 g of aramid fibrid, and 02261 aramid pulp fiber were placed in a fiber disintegrator, 13 ml of 1 wt% polyethylene oxide solution and 1.1 L of deionized water were added, and the mixture was fully disintegrated for 30,000 revolutions to obtain mixed fiber A; S2, using a wet forming process to prepare a wet paper web B by mixing mixed fiber A and deionized water in a ratio of 1.1L:7.5L on a standard paper machine; S3, the wet paper web B is first cold pressed at 8 MPa for 5 min, then vacuum dried at 102°C for 10 min, and finally hot pressed at 13 MPa and 200°C for 12 min to obtain a high temperature resistant polyphenylene sulfide fiber composite insulation paper product C.

[0037] The dielectric properties of the high temperature resistant polyphenylene sulfide fiber composite insulation paper product C obtained in Example 4 are as follows: the thickness is 0.100 mm, the mechanical strength can reach 36.2 N / cm, the dielectric strength can reach 4.80 kV / mm, and the dielectric constant is only 0.02 (10 4 Hz).

[0038] Example 5 S1, 1.0048 g of polyphenylene sulfide fiber, 1.2560 g of aramid fibrid, and 0.2512 g of aramid pulp fiber were placed in a fiber disintegrator, 15 ml of 1 wt% polyethylene oxide solution and 1.2 L of deionized water were added, and the mixture was fully disintegrated for 35,000 revolutions to obtain mixed fiber A; S2, using a wet forming process to prepare a wet paper web B by mixing mixed fiber A and deionized water in a ratio of 1.2L:7L on a standard paper machine; S3, the wet paper web B is first cold pressed at 10 MPa for 5 min, then vacuum dried at 100°C for 10 min, and finally hot pressed at 13 MPa and 200°C for 10 min to obtain a high temperature resistant polyphenylene sulfide fiber composite insulation paper product C.

[0039] The dielectric properties of the high temperature resistant polyphenylene sulfide fiber composite insulation paper product C obtained in Example 5 are as follows: the thickness is 0.116 mm, the mechanical strength can reach 23.7 N / cm, the dielectric strength can reach 4.59 kV / mm, and the dielectric constant is only 0.03 (10 4 Hz).

[0040] Table 1 shows the polyphenylene sulfide / aramid composite paper prepared in Examples 1 to 5. It can be seen that the high temperature resistant polyphenylene sulfide fiber composite insulation paper prepared by the process provided by the present invention has a thickness in the range of 0.100 mm to 0.135 mm, a dielectric strength in the range of 3.06 to 4.80, and a 4 The dielectric constant at Hz is in the range of 0.01~0.03.

[0041] Table 1 High temperature resistant polyphenylene sulfide fiber composite insulation paper and related technical parameters

[0042] The high temperature resistant polyphenylene sulfide fiber composite insulation paper prepared in Examples 1 to 5 has good strength performance, high temperature stability and excellent dielectric properties. Figure 2 and Figure 3 It can be seen that the aramid fibrils in the high temperature resistant polyphenylene sulfide fiber composite insulation paper prepared by the present invention are randomly distributed and evenly and tightly interwoven with the polyphenylene sulfide fibers, constructing a dense structure similar to "rebar-mortar", which improves its mechanical strength while reducing the current path, thereby avoiding the accumulation of charges in pores and defects, reducing the local electric field strength, and achieving an overall improvement in dielectric strength. Figure 6 and Figure 7 It can be seen that when the PPS content is 40 wt%, the tensile strength of the paper sample is 2.37 kN / m and the dielectric strength is 4.59 kV / mm.

[0043] Depend on Figure 4 and Figure 5 It can be seen that with the increase of frequency, the dielectric constant and dielectric loss of polyphenylene sulfide fiber composite paper gradually decrease. When the frequency is large enough, both tend to be stable. When the polyphenylene sulfide fiber content is 45 wt%, the composite paper is 10 4 The dielectric constant at Hz is 1.44, and the dielectric properties are excellent.

[0044] Depend on Figure 8 It can be seen that the limiting oxygen index of composite paper with different polyphenylene sulfide fiber content is not much different, about 26%, which has better flame retardant properties than the conventional cellulose insulation paper of 18%.

[0045] Depend on Fig. 9 and 10 It can be seen that the initial decomposition temperatures of the composite papers of Examples 3, 4 and 5 are not much different, all close to 360°C. After high-temperature treatment at 800°C, the residual mass fraction of the composite paper remains above 40%, and the thermal stability is excellent.

[0046] The present invention also discloses a process for preparing composite insulating paper from polyphenylene sulfide fiber and aramid fiber precipitate to prepare high temperature resistant polyphenylene sulfide fiber composite insulating paper. Figure 3 As shown in the figure, the dense structure similar to "rebar-mortar" of the composite paper has excellent heat resistance and chemical corrosion resistance, and the production process is short and pollution-free, which can reduce its industrial production cost, improve the heat resistance and chemical stability of insulating paper for mid- and low-end applications to a certain extent, and broaden its application areas in more severe environments, with good economic benefits and application value.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A high temperature resistant polyphenylene sulfide fiber composite insulation paper and its preparation process, characterized in that: The following steps are involved: S1, using polyethylene oxide solution as a dispersant and water to decompose polyphenylene sulfide fiber, meta-aramid fibrid and para-aramid pulp fiber to obtain mixed fiber A; S2, using a wet forming process to vacuum filter and dehydrate the mixed fiber A to form a wet paper web B; S3, the wet paper web B is subjected to cold pressing treatment, vacuum drying treatment and hot pressing treatment in sequence to obtain a high temperature resistant polyphenylene sulfide fiber composite insulating paper C.

2. The process for preparing high temperature resistant polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S1, the length of polyphenylene sulfide fiber is 3-6mm, the fineness is 0.75-0.89dtex; the average fiber length of meta-aramid fibrillation is 0.6-1.0mm, the degree of fibrillation is 45-55°SR, and the specific surface area is 8-12m 2 / g; the average fiber length of para-aramid pulp fiber is 0.9-1.3mm, the degree of fibrillation is 40-48°SR, and the specific surface area is 7.5-10m 2 / g.

3. The process for preparing polyphenylene sulfide fiber composite insulating paper according to claim 1, characterized in that: In S1, the mass ratio of polyphenylene sulfide fiber, aramid fibrid and aramid pulp fiber is (40-60) wt%: (35-55) wt%: (5-10) wt%.

4. The process for preparing polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S1, the concentration of the polyethylene oxide solution is 0.1wt%-1wt%.

5. The process for preparing polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S1, the ratio of polyphenylene sulfide fiber, aramid fiber, aramid pulp fiber, dispersant and deionized water is (1.0048-1.5072) g:(0.8541-1.2560) g:(0.1507-0.2512) g:(10-20) mL:(0.8-1.2) L.

6. The process for preparing polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S2, the parameters of the wet forming process are: dehydration time is 5-10s, and vacuum suction pressure is 1-5MPa.

7. The process for preparing high temperature resistant polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S3, during the cold pressing process, the pressure is 5-10 MPa and the pressing time is 5-8 min.

8. The process for preparing high temperature resistant polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S3, during the vacuum drying treatment, the temperature is 100-105°C, the vacuum degree is 0.6-0.9MPa, and the drying time is 10-15min.

9. The process for preparing high temperature resistant polyphenylene sulfide fiber composite insulation paper according to claim 1, characterized in that: In S3, during the hot pressing treatment, the pressure is 13-15 MPa, the temperature is 180-200° C., and the time is 10-15 min.

10. A high temperature resistant polyphenylene sulfide fiber composite insulating paper prepared by the high temperature resistant polyphenylene sulfide fiber composite insulating paper preparation process according to any one of claims 1 to 9.

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