SMC sheet for cable protection, U-shaped fireproof plate and preparation method thereof

Abstract

The application belongs to the technical field of cable protection, and particularly relates to an SMC sheet for cable protection, a U-shaped fireproof plate and a preparation method thereof. The SMC sheet for cable protection is prepared from the following raw materials in parts by mass: 75-85 parts of phenolic resin, 95-105 parts of mesophase pitch-based carbon fiber, 220-240 parts of halogen-free flame retardant, 6-8 parts of diluent, 8-10 parts of internal release agent, 1.5-2.5 parts of catalyst, 0.5-1.5 parts of thickening agent and 0.5-3 parts of coupling agent. The catalyst is aniline or polyaniline doped with polyphosphoric acid. The phenolic resin is used as the resin matrix, and the aniline or polyaniline doped with polyphosphoric acid is used as the catalyst, so that the prepared SMC material has excellent flame retardant performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cable protection, and particularly relates to an SMC sheet for cable protection, a U-shaped fireproof plate and a preparation method thereof. BACKGROUND

[0002] The SMC sheet is a sheet molding compound composed of resin, filler, thickening agent, mold release agent and the like, and is pressed by a special process. It has good mechanical properties, corrosion resistance, weather resistance and electrical insulation. It is widely used in the preparation of protective materials in the field of cables.

[0003] The patent document with the publication number CN108034212A discloses a preparation method of a low-shrinkage flame-retardant sheet molding compound. The preparation method uses a silane coupling agent to modify the surface of calcium carbonate, improves the compatibility of calcium carbonate and resin, reduces the shrinkage rate of the sheet molding compound, and improves the surface gloss. Phosphoric acid is used to modify magnesium chloride hexahydrate and light burned magnesite powder. During the combustion process, a dense carbon layer structure appears on the surface of the substrate, which plays a heat insulation role and is beneficial to the flame retardance of the sheet molding compound. The patent document with the publication number CN114230996A discloses a new flame-retardant SMC sheet and a preparation method thereof. The preparation method adds a proper amount of halogenated saturated dibasic acid anhydride during the production and preparation of unsaturated polyester resin to obtain better flame-retardant effect, can replace the banned bromine-containing flame-retardant additives due to environmental protection problems, and reduces the use amount of other flame-retardant materials in the SMC product under the same conditions, thereby avoiding adverse effects on human health and ecology. However, the oxygen index of the SMC sheet prepared by the two patent documents is only about 25-30%.

[0004] The SMC sheet is mainly used as a fireproof plate in the field of cable protection. With the rapid development of economy, cables are increasingly widely used. Once the cable short-circuits or a fire occurs due to other reasons, it may cause incalculable losses. Therefore, in the field of cable protection, the flame-retardant performance of the SMC sheet is increasingly required. For example, the SMC material with a high oxygen index can significantly reduce the fire size and the resulting losses during a fire. Therefore, the requirements for the flame retardance, oxygen index and smoke density of the SMC sheet are increasingly stringent in the field of cable protection. The SMC sheet with an oxygen index of 25-30% cannot meet the needs of the cable industry. How to improve the flame retardance, oxygen index and reduce the smoke density of the SMC sheet has become a technical problem to be solved in the field of cable protection. SUMMARY

[0005] To solve the drawbacks of the prior art, the application discloses an SMC sheet for cable protection, which adopts the following technical scheme:

[0006] An SMC sheet for cable protection, raw materials of the SMC sheet in mass parts include: 75-85 parts of phenolic resin, 95-105 parts of mesophase pitch-based carbon fiber, 220-240 parts of halogen-free flame retardant, 6-8 parts of diluent, 8-10 parts of internal release agent, 1.5-2.5 parts of catalyst, 0.5-1.5 parts of thickening agent and 0.5-3 parts of coupling agent,

[0007] The catalyst is aniline or polypolyphosphoric acid doped polyaniline.

[0008] In the prior art, anhydride catalysts or imidazole amine catalysts are often used as catalysts for the preparation of SMC sheets. The anhydride catalysts have long curing time, high curing temperature and poor corrosion resistance. The imidazole amine catalysts need strict control of the addition amount, curing temperature and curing time during the production of phenolic resin, and the production conditions are harsh. When the aniline or polypolyphosphoric acid doped polyaniline of the present application is used as a catalyst, the curing effect is better. The present inventors have also found that the aniline or polypolyphosphoric acid doped polyaniline can significantly improve the flame retardance and oxygen index of the SMC material when preparing the SMC sheet, which cannot be achieved by using anhydride catalysts or imidazole catalysts.

[0009] Further, the preparation method of the polypolyphosphoric acid doped polyaniline is as follows:

[0010] The polypolyphosphoric acid is used as a dopant, aniline is used as a monomer, and an oxidation polymerization method of persulfate is used for preparation. The molar ratio of the persulfate to the aniline is 1:1, and the molar ratio of the polypolyphosphoric acid to the aniline is 2:1.

[0011] Further, in the preparation method of the polypolyphosphoric acid doped polyaniline, the reaction temperature is 15℃±3℃, the reaction time is 1.5-2.5h, the dropping time of the persulfate is 50-70min, and the initial reaction concentration of the polypolyphosphoric acid is 1.4-1.6mol / L. Preferably, the persulfate is ammonium persulfate.

[0012] Preferably, the reaction temperature is 15℃, the reaction time is 2h, the dropping time of the ammonium persulfate is 60min, and the initial reaction concentration of the polypolyphosphoric acid is 1.5mol / L.

[0013] Further, the halogen-free flame retardant is ultra-fine aluminum hydroxide, and the particle size of the ultra-fine aluminum hydroxide is 5-10μm. The use of ultra-fine aluminum hydroxide as a halogen-free flame retardant has the advantages of stable physical and chemical properties at room temperature, no secondary pollution during combustion, high whiteness, excellent color index, improved limited oxygen index of the flame-retardant polymer, increased flame-retardant performance, improved surface smoothness of the polymer product, and enhanced mechanical and electrical properties, anti-tracking, arc resistance and wear resistance.

[0014] The diluent is any one of ethanol, methanol and ethylene glycol, the phenolic resin is high in viscosity and poor in fluidity during processing, the addition of the diluent can effectively reduce the viscosity of the resin, so that the resin is easy to handle and the processing performance is improved, and the curing speed of the phenolic resin can be adjusted to a certain extent.

[0015] The internal release agent is zinc stearate or lecithin;

[0016] The thickening agent is magnesium oxide;

[0017] The coupling agent is a silane coupling agent.

[0018] Further, the mesophase pitch-based carbon fiber is a chopped mesophase pitch-based carbon fiber.

[0019] Further, the oxygen index of the SMC sheet with a thickness of 5mm is ≥50%, the flame-retardant grade of the SMC sheet is V0, and the smoke density is ≤12mg / cm 3 The flame-retardant performance is excellent, can reach UL-94-V-0 level, and also has good physical and mechanical properties and high heat distortion temperature.

[0020] The application also discloses a preparation method of the SMC sheet for cable protection.

[0021] 1) weighing the preparation raw materials;

[0022] 2) adding the phenolic resin, the diluent and the internal release agent into a stirring pot and mixing uniformly, and then adding the catalyst, the thickening agent and the coupling agent into the stirring pot and mixing uniformly;

[0023] 3) adding the halogen-free flame retardant into the stirring pot and mixing uniformly to obtain a resin paste;

[0024] 4) controlling the water content of the resin paste in 0.10-0.15% and the viscosity within 150-200mpa·s;

[0025] 5) after the mesophase pitch carbon fiber is fully immersed in the resin paste obtained in step 4), starting an SMC forming machine to form;

[0026] 6) winding the product prepared in step 5) and sending to a thickening chamber for thickening treatment to obtain an SMC sheet.

[0027] Further, in step 6), the temperature of the thickening treatment is 40-70℃, the time is 30-40min, and then the temperature is increased to 80℃±1℃ and the reaction is continued for 20-30min.

[0028] The application also discloses a preparation method of a U-shaped fireproof plate for cable protection.

[0029] The SMC sheet is prepared by the method for preparing the SMC sheet for cable protection.

[0030] The SMC sheet is pressed at 130-160 DEG C, the pressure is 800-1000t / m 2 , and the mold pressing time is 3-5 min.

[0031] The application further discloses a U-shaped fireproof plate for cable protection.

[0032] The first plate body and the second plate body are prepared by the method for preparing the U-shaped fireproof plate for cable protection.

[0033] The U-shaped fireproof plate of the application has low requirement on installation space and is suitable for various narrow environments.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] 1. The SMC sheet of the application selects phenolic resin as the resin matrix, and the phenolic resin has an aromatic ring structure in the main chain, so that the SMC sheet has a high oxygen index and is relatively stable at high temperature and is not easy to burn.

[0036] 2. The application selects aniline or polyaniline doped with polyphosphoric acid as the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0037] Fig. 1 Figure 1 is a schematic view of a first plate body structure of a U-shaped fireproof plate for cable protection in Example 7;

[0038] Fig. 2 Figure 2 is a schematic view of a second plate body structure of a U-shaped fireproof plate for cable protection in Example 7;

[0039] Fig. 3 Figure 3 is a schematic view of an assembled structure of a U-shaped fireproof plate for cable protection in Example 7.

[0040] In the figure, 1 is a first plate body, and 2 is a second plate body. DETAILED DESCRIPTION

[0041] The technical solutions described in the present application will be described clearly and completely in combination with specific embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present application and do not have any limiting effect.

[0042] The raw materials used in the examples and comparative examples of the present application are all ordinary commercially available products.

[0043] The product performance detection method of the examples and comparative examples of the present application is as follows:

[0044] Flame retardant grade: the sample is subjected to 2 times of 10S combustion test, and the flame extinguishing time and whether there is burning material falling are observed.

[0045] The oxygen index is detected according to GB / T2406-2009, and the smoke density is detected according to GB / T 8627-2007.

[0046] The thickness of the sample is 5mm.

[0047] Example 1

[0048] The present embodiment discloses a preparation method of an SMC sheet:

[0049] The preparation raw materials of the SMC sheet and the mass parts thereof are as follows: phenolic resin 80 parts, mesophase pitch-based carbon fiber 100 parts, diluent (ethanol) 7 parts, internal release agent (lecithin) 8 parts, catalyst (aniline) 2 parts, halogen-free flame retardant (ultra-fine aluminum hydroxide, particle size 5-10μm) 230 parts, thickening agent (magnesium oxide) 1 part, coupling agent (silane coupling agent) 2 parts.

[0050] The specific preparation method is as follows:

[0051] 1) The above preparation raw materials are weighed.

[0052] 2) The phenolic resin, diluent and internal release agent are mixed into a stirring pot and stirred, and the stirring time is controlled to be within 5min. Then the catalyst, thickening agent and coupling agent are mixed therein, and continue to stir for 3min to ensure uniform mixing.

[0053] 3) Finally, add halogen-free flame retardant into it, stir for 5 min.

[0054] 4) Test the formed resin paste for moisture and viscosity, control the moisture content within 0.1-0.15%, and control the viscosity within 150-200 mpa.s;

[0055] 5) Pour the qualified resin paste into the standby pot, and at the same time, immerse the intermediate pitch-based carbon fiber into the resin paste by using the chopped intermediate pitch-based carbon fiber, so that it is fully infiltrated, and start the SMC molding machine to form.

[0056] 6) The product is checked for rolling, and is sent to the thickening room, the thickening temperature is 45°C, the time is 40 min, then the temperature is raised to 80°C, and the reaction is continued for 30 min.

[0057] After 2 times of 10S combustion test, the flame of the SMC sheet prepared in this embodiment is extinguished within 30S, no burning matter falls, the flame retardant level is V-0 level, the oxygen index is 51%, and the smoke density is 12 mg / cm 3 .

[0058] Example 2

[0059] The embodiment discloses a preparation method of an SMC sheet, which is different from that of example 1 only in that:

[0060] The raw materials for preparing the SMC sheet and the mass parts thereof are as follows: phenolic resin 85 parts, intermediate pitch-based carbon fiber 95 parts, diluent (ethanol) 6 parts, internal release agent (zinc stearate) 10 parts, catalyst (aniline) 1.5 parts, halogen-free flame retardant (ultrafine aluminum hydroxide) 220 parts, thickening agent (magnesium oxide) 1.5 parts, and coupling agent (silane coupling agent) 1 part.

[0061] In the specific preparation method, 6) the product is checked for rolling, and is sent to the thickening room, the thickening temperature is 70°C, the time is 30 min, then the temperature is raised to 80°C, and the reaction is continued for 20 min.

[0062] The other steps are the same as those of example 1.

[0063] After 2 times of 10S combustion test, the flame of the SMC sheet prepared in this embodiment is extinguished within 30S, no burning matter falls, the flame retardant level is V-0 level, the oxygen index is 51%, and the smoke density is 12 mg / cm 3 .

[0064] Example 3

[0065] The embodiment discloses a preparation method of an SMC sheet:

[0066] The difference from Example 1 is that the catalyst is polyphosphoric acid doped polyaniline.

[0067] The preparation method of the polyphosphoric acid doped polyaniline is as follows: polyphosphoric acid is used as a dopant, aniline is used as a monomer, and an ammonium persulfate oxidation polymerization method is used for preparation, the molar ratio of the ammonium persulfate to the aniline is 1:1, the molar ratio of the polyphosphoric acid to the aniline is 2:1, the reaction temperature is 18°C, the reaction time is 1.5h, the dropping time of the ammonium persulfate is 70min, and the initial reaction concentration of the polyphosphoric acid is 1.6mol / L.

[0068] The other steps are the same as those in Example 1.

[0069] It is detected that, after the SMC sheet prepared in the embodiment is subjected to 2 times of 10S combustion test, the flame is extinguished within 30S, no burning matter falls, the flame retardant level is V-0 level, the oxygen index is 53%, and the smoke density is 10mg / cm 3 .

[0070] Example 4

[0071] The embodiment discloses a preparation method of an SMC sheet.

[0072] The difference from Example 3 is that, when the polyphosphoric acid doped polyaniline is prepared, the reaction temperature is 15°C, the reaction time is 2h, the dropping time of the ammonium persulfate is 60min, and the initial reaction concentration of the polyphosphoric acid is 1.5mol / L.

[0073] The other steps are the same as those in Example 3.

[0074] It is detected that, after the SMC sheet prepared in the embodiment is subjected to 2 times of 10S combustion test, the flame is extinguished within 30S, no burning matter falls, the flame retardant level is V-0 level, the oxygen index is 58%, and the smoke density is 8mg / cm 3 .

[0075] Example 5

[0076] The embodiment discloses a preparation method of an SMC sheet.

[0077] The difference from Example 4 is that the adding amount of the polyphosphoric acid doped polyaniline is 2.5 parts.

[0078] The other steps are the same as those in Example 4.

[0079] It is detected that, after the SMC sheet prepared in the embodiment is subjected to 2 times of 10S combustion test, the flame is extinguished within 30S, no burning matter falls, the flame retardant level is V-0 level, the oxygen index is 55%, and the smoke density is 10mg / cm 3 .

[0080] Example 6

[0081] This embodiment discloses a method for preparing SMC sheets:

[0082] The only difference from Example 4 is that the amount of polyphosphoric acid-doped polyaniline added is 1.5 parts.

[0083] The other steps are the same as in Example 4.

[0084] Testing showed that the SMC sheet prepared in this embodiment extinguished the flame within 30 seconds after two 10-second burning tests, with no burning material falling off, achieving a flame retardant rating of V-0; an oxygen index of 53%; and a smoke density of 9 mg / cm³. 3 .

[0085] Example 7

[0086] This embodiment discloses a U-shaped fireproof board for cable protection, such as... Figs. 1-3 As shown, it includes a first plate 1 and a second plate 2. The first plate 1 is provided with a protrusion and a first mounting hole, and the second plate 2 is provided with a groove and a second mounting hole. The first plate 1 and the second plate 2 are fastened together by the protrusion and the groove. After the first plate 1 and the second plate 2 are fastened together, they are fixedly connected by rivets, the first mounting hole and the second mounting hole. The first plate 1 and the second plate 2 form a "U" shape after being connected.

[0087] The preparation methods for the first plate 1 and the second plate 2 are as follows:

[0088] The SMC sheet prepared in Example 1 was pressed at 150°C under a pressure of 900 t / m. 2 The molding time is 5 minutes.

[0089] Comparative Example 1

[0090] This comparative example discloses a method for preparing SMC sheets:

[0091] The difference from Example 1 is that the catalyst is phthalic anhydride.

[0092] The other steps are the same as in Example 1.

[0093] Testing showed that the SMC sheet prepared in this comparative example extinguished its flame within 10 seconds after two 10-second burning tests, with no burning material falling off, achieving a flame retardant rating of V-1; an oxygen index of 48%; and a smoke density of 12 mg / cm³. 3 .

[0094] Comparative Example 2

[0095] This comparative example discloses a method for preparing SMC sheets:

[0096] The difference from Example 1 is that the catalyst is imidazole.

[0097] The other steps are the same as Example 1.

[0098] After 2 times 10S combustion test, the flame of the SMC sheet prepared in this comparative example is extinguished within 15S, no burning material falls, the flame retardant level is V-1 level; the oxygen index is 45%; the smoke density is 10 mg / cm 3 .

[0099] Comparative Example 3

[0100] This comparative example discloses a preparation method of an SMC sheet:

[0101] The difference from Example 4 is that 80 parts of epoxy resin is added to replace the phenolic resin.

[0102] The other steps are the same as Example 1.

[0103] After 2 times 10S combustion test, the flame of the SMC sheet prepared in this comparative example is extinguished within 60S, no burning material falls, the flame retardant level is V-2 level; the oxygen index is 26%; the smoke density is 16 mg / cm 3 .

[0104] Comparative Example 4

[0105] This comparative example discloses a preparation method of an SMC sheet:

[0106] The difference from Example 4 is that 80 parts of vinyl resin is added to replace the phenolic resin.

[0107] The other steps are the same as Example 1.

[0108] After 2 times 10S combustion test, the flame of the SMC sheet prepared in this comparative example is extinguished within 60S, no burning material falls, the flame retardant level is V-1 level; the oxygen index is 31%; the smoke density is 20 mg / cm 3 .

[0109] Comparative Example 5

[0110] This comparative example discloses a preparation method of an SMC sheet:

[0111] The difference from Example 4 is that the amount of polyaniline doped with polyphosphoric acid is 1.0 part.

[0112] The other steps are the same as Example 4.

[0113] The SMC sheet prepared in the present comparative example is subjected to 2 times of 10S combustion test, the flame is extinguished within 60S, no burning matter drops, the flame retardant level is V-1 level; the oxygen index is 56%; the smoke density is 9mg / cm 3 .

[0114] Comparative example 6

[0115] The present comparative example discloses a preparation method of SMC sheet:

[0116] The difference from example 4 is that the adding amount of polyaniline doped with polyphosphoric acid is 3.0 parts.

[0117] The other steps are the same as example 4.

[0118] The SMC sheet prepared in the present comparative example is subjected to 2 times of 10S combustion test, the flame is extinguished within 60S, no burning matter drops, the flame retardant level is V-1 level; the oxygen index is 57%; the smoke density is 10mg / cm 3 .

[0119] It can be concluded from examples 1-6 that the flame retardant level of the SMC sheet prepared in the present application is V-0 level; the oxygen index is greater than or equal to 50%; the smoke density is less than or equal to 12mg / cm 3 , and the comprehensive performance is better.

[0120] It can be seen from examples 1, examples 3-4 and comparative examples 1-2 that, by selecting aniline and polyaniline doped with polyphosphoric acid as catalyst, the oxygen index of the prepared SMC sheet is improved and the flame retardant level is better compared with the conventional catalyst selected in the prior art for preparing SMC. Meanwhile, the transverse comparison of examples 1 and examples 3-4 shows that the effect is better when polyaniline doped with polyphosphoric acid is selected.

[0121] It can be seen from example 4 and comparative examples 1-2, comparative examples 3-4 that the catalyst and phenol resin selected in the present application can coordinate and synergize, so that the comprehensive performance of the prepared SMC sheet is better.

[0122] It can be seen from examples 4-6 and comparative examples 5-6 that the adding amount of catalyst should be controlled within the range of 1.5-2.5, and when the adding amount is too low or too high, the flame retardant performance of the SMC sheet will be affected.

Claims

1. An SMC sheet for cable protection, characterized in that: The raw materials for preparing the SMC sheet, by weight, include: 75-85 parts phenolic resin, 95-105 parts mesophase pitch-based carbon fiber, 220-240 parts halogen-free flame retardant, 6-8 parts diluent, 8-10 parts internal release agent, 1.5-2.5 parts catalyst, 0.5-1.5 parts thickener, and 0.5-3 parts coupling agent; The catalyst is polyphosphoric acid-doped polyaniline; The method for preparing the polyphosphoric acid-doped polyaniline is as follows: It is prepared by persulfate oxidative polymerization using polyphosphoric acid as a dopant and aniline as a monomer. The molar ratio of persulfate to aniline is 1:1, and the molar ratio of polyphosphoric acid to aniline is 2:

1.

2. The SMC sheet for cable protection according to claim 1, characterized in that: In the method for preparing polyphosphoric acid-doped polyaniline, the reaction temperature is 15℃±3℃, the reaction time is 1.5~2.5h, the persulfate is added in 50~70min, and the initial reaction concentration of polyphosphoric acid is 1.4~1.6mol / L.

3. The SMC sheet for cable protection according to claim 1, characterized in that: The halogen-free flame retardant is ultrafine aluminum hydroxide, and the particle size of the ultrafine aluminum hydroxide is 5~10μm; The diluent is any one of ethanol, methanol, and ethylene glycol; The internal release agent is zinc stearate and lecithin; The thickener is magnesium oxide; The coupling agent is a silane coupling agent.

4. The SMC sheet for cable protection according to claim 1, characterized in that: The mesophase pitch-based carbon fiber is a short-cut mesophase pitch-based carbon fiber.

5. The SMC sheet for cable protection according to claim 1, characterized in that: The oxygen index of 5mm thick SMC sheets is ≥50%, the flame retardancy rating of SMC sheets is V0, and the smoke density is ≤12mg / cm³. 3 .

6. A method for preparing an SMC sheet for cable protection as described in any one of claims 1 to 5, characterized in that: Includes the following steps: 1) Weigh the raw materials for preparation; 2) Add phenolic resin, diluent and internal release agent to the mixing pot and mix evenly. Then add catalyst, thickener and coupling agent to the mixing pot and mix evenly. 3) Add the halogen-free flame retardant to the mixing pot and mix well to obtain a resin paste; 4) The moisture content of the resin paste is controlled at 0.10~0.15%, and the viscosity is controlled within 150-200 mPa·s; 5) After fully impregnating the mesophase pitch carbon fiber in the resin paste obtained in step 4), start the SMC molding machine to form it; 6) The product obtained in step 5) is wound up and sent to the thickening chamber for thickening treatment to obtain SMC sheet.

7. The preparation method according to claim 6, characterized in that: In step 6), the thickening treatment temperature is 40~70°C and the time is 30-40 min. Then the temperature is increased to 80°C±1°C and the reaction continues for 20-30 min.

8. A method for preparing a U-shaped fireproof board for cable protection, characterized in that: Includes the following steps: SMC sheets are prepared using the method for preparing SMC sheets for cable protection as described in claim 6 or claim 7; The SMC sheet was pressed at 130-160°C under a pressure of 800-1000 t / m. 2 The molding time is 3-5 minutes.

9. A U-shaped fireproof board for cable protection, characterized in that: It includes a first plate and a second plate. The first plate has a protrusion and a first mounting hole, and the second plate has a groove and a second mounting hole. The first plate and the second plate are fastened together by the protrusion and the groove. After the first plate and the second plate are fastened together, they are fixedly connected by rivets, the first mounting hole and the second mounting hole. The first plate and the second plate are connected in a "U" shape. The first plate and the second plate are prepared using the method for preparing U-shaped fireproof plates for cable protection as described in claim 8.

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