A compound for transparent flame-retardant coating, and a preparation method and application thereof

Abstract

The present application relates to a kind of transparent flame-retardant coating compound and its preparation method and application, the structural formula of the compound is as shown below: preparation method includes with diphenyl phosphor chloride (DPPC), tetraethylenepentamine (TEPA), ladder epoxy polysiloxane (AEOS) as raw material, by two-step method polymerization is obtained.The transparent flame-retardant coating compound of the present application is used for polycarbonate coating, with the characteristics of strong adhesion, high surface hardness, excellent transparency and flame-retardant performance, has good market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of functional coating technology, and specifically relates to a transparent flame-retardant coating compound, its preparation method, and its application. Background Technology

[0002] Polycarbonate (PC), as one of the most widely used engineering plastics, boasts high impact strength, high transparency, heat resistance, and dimensional stability. However, its flame retardant properties are lacking. Current methods for flame-retardant modification of PC, whether additive or intrinsic flame retardant, all negatively impact its transparency and mechanical properties. Applying a transparent flame-retardant coating can ensure that the excellent mechanical properties and transparency of PC sheets remain unaffected while simultaneously improving its flame retardancy. However, a polycarbonate coating material that combines both transparency and flame retardancy is still lacking. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a transparent flame-retardant coating compound, its preparation method and application. When this compound is used in polycarbonate coatings, it has the characteristics of strong adhesion, high surface hardness, excellent transparency and flame retardant properties, and has good market application prospects.

[0004] This invention provides a compound for a transparent flame-retardant coating, the structural formula of which is shown below:

[0005]

[0006] This invention also provides a method for preparing a compound for a transparent flame-retardant coating, comprising the following steps:

[0007] (1) Weigh out tetraethylenepentamine TEPA and dissolve it in an organic solvent. At the same time, add anhydrous K2CO3 and stir mechanically. Place it in an ice-water bath environment for later use. Dissolve diphenylphosphine chloride DPPC in an organic solvent and add it dropwise to the TEPA solution under N2 atmosphere. After the addition is complete, continue stirring at room temperature. After the reaction is complete, the product 1,11-bis[(oxoylidediphenyl-λ5-methylphospho)amino]-3,6,9-triazaundecane (DPTEPA) is obtained by post-treatment.

[0008] (2) The DPTEPA and ladder-shaped epoxy polysiloxane AEOS obtained above are dissolved in a mixed solution of ethanol and acetonitrile to obtain a transparent flame-retardant coating compound.

[0009] Preferably, the molar ratio of TEPA to DPPC in step (1) is 1:1.5-2.5.

[0010] Preferably, the concentration of the TEPA solution in step (1) is (5-6)*10. -4mol / L; DPPC solution concentration is (1-2)*10 -3 mol / L.

[0011] Preferably, the organic solvent in step (1) is dichloromethane.

[0012] Preferably, the molar ratio of anhydrous K2CO3 to TEPA in step (1) is 1:0.4-0.8.

[0013] Preferably, the molar ratio of DPTEPA to AEOS in step (2) is 0.5-1.5:1.

[0014] Preferably, the preparation method of AEOS in step (2) includes the following steps: reacting γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH560 at room temperature under the conditions of THF and anhydrous K2CO3, and obtaining ladder-shaped epoxy polysiloxane AEOS after post-treatment.

[0015] Preferably, the volume ratio of ethanol to acetonitrile in the ethanol-acetonitrile mixed solution in step (2) is 1:1.

[0016] The present invention also provides the application of a transparent flame-retardant coating compound in the flame-retardant treatment of polycarbonate.

[0017] Beneficial effects

[0018] The transparent flame-retardant coating compound of this invention is used in polycarbonate coatings and has the characteristics of strong adhesion, high surface hardness, excellent transparency and flame retardant properties, and has good market application prospects. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation route of DPTEPA in this invention.

[0020] Figure 2 This is a schematic diagram of the preparation route of the trapezoidal epoxy polysiloxane (AEOS) in this invention.

[0021] Figure 3 This is a schematic diagram of the preparation route of the compound for the transparent flame-retardant coating in this invention.

[0022] Figure 4 This is a digital photograph of the transparent flame-retardant coating in this invention.

[0023] Figure 5 (a) shows the infrared spectra of the reactants and product DPTEPA; (b) and (c) show the infrared spectra of DPTEPA, respectively. 1 H and 31(d) is the NMR spectrum of AEOS; (e) is the infrared spectrum of samples cured with five different ratios of reactive H to epoxy groups; (f) is the NMR spectrum of AEOS. 29 Si NMR spectrum; (f) shows the coating of DPTEPA. 1.25 - SEM images and elemental distribution diagrams of the PC substrate surface with AEOS1 coating.

[0024] Figure 6 (a) and (b) are digital photographs and UV-Vis transmission spectra of PC sheets and their coatings, respectively; (c) and (d) are DPTEPA coatings, respectively. 1.25 - Digital photos of the adhesion test of the AEOS1 coating on the PC substrate and photos of the hydrophobic angle of the coating.

[0025] Figure 7 (a) and (b) are the thermogravimetric data of PC sheets and their coatings under nitrogen.

[0026] Figure 8 These are cone calorimeter test data for PC sheets and their coatings.

[0027] Figure 9 These are digital photos of the residual carbon and SEM photos of the carbon slag after cone calorimetry testing of PC sheets and their coating composites.

[0028] Figure 10 (a) is DPTEPA 1.25 - FTIR spectra of the AEOS1 coating during pyrolysis. (b) FTIR spectra of polycarbonate and coating residue. (c) FTIR spectra of DPTEPA. 1.25 - Digital photograph of AEOS1 spline vertical combustion test. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] The compounds for transparent flame-retardant coatings and the methods for applying these coatings are as follows:

[0031] Step 1: As Figure 1As shown, 8.69 g of tetraethylenepentamine (TEPA) and 90 ml of dichloromethane solution were weighed into a 250 ml three-necked flask, and 13.8 g of anhydrous K₂CO₃ was added simultaneously. The mixture was mechanically stirred, and the flask was placed in an ice-water bath at 0 °C. Then, 21.3 g of diphenylphosphine chloride (DPPC) was weighed and dissolved in 60 ml of dichloromethane solution. The solution was slowly added dropwise to the three-necked flask under a nitrogen atmosphere. After the addition was complete, the mixture was stirred at room temperature for 8 hours. After the reaction was complete, the mixture was filtered through a Buchner funnel, and the dichloromethane was removed by rotary evaporation to obtain a pale yellow, transparent, viscous substance, which was the reaction product DPTEPA.

[0032] Step 2: As Figure 3 As shown, a certain amount (total weight 16g) of DPTEPA and AEOS was dissolved in 30ml of a 1:1 mixture of ethanol and acetonitrile to prepare DPTEPA. x -AEOS1 coating solution, where x represents the ratio of the number of active H atoms in DPTEPA to the number of epoxy groups in AEOS, x = 0.5-1.5, which is the transparent flame-retardant coating compound of the present invention. The resulting pale yellow transparent solution is dropped onto untreated PC sheets, ensuring a dry weight of 400 g / m². 2 The coatings were cured at 60°C for 4 hours and then at 80°C for 24 hours in a constant-temperature drying oven. Following this method, five hybrid coatings with different proportions were prepared; detailed formulations are shown in Table 1.

[0033] The ladder-shaped epoxy polysiloxane (AEOS) is prepared by the following method:

[0034] like Figure 2 As shown, 30 g of deionized water and 0.25 g of anhydrous K₂CO₃ were weighed and added to a 500 ml three-necked round-bottom flask, and stirred magnetically for 10 min. Then, 200 ml of tetrahydrofuran (THF) was poured into the mixture and stirred magnetically for 20 min. 118 g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560) was added dropwise under a N₂ atmosphere, and the reaction was carried out at room temperature for 48 hours. THF was then removed by rotary evaporation to obtain a transparent, viscous substance. This substance was diluted with dichloromethane solution, dried over anhydrous MgSO₄ for 12 hours, and filtered through a Buchner funnel to remove MgSO₄, yielding a transparent, viscous, ladder-shaped epoxy polysiloxane (AEOS).

[0035] Example 1

[0036] Accurately weigh 2.79 g of DPTEPA and 13.21 g of AEOS and dissolve them in 30 ml of a 1:1 mixture of ethanol and acetonitrile to prepare DPTEPA. 0.5-AEOS1 coating solution, where 0.5 represents the ratio of reactive H in DPTEPA to the number of epoxy groups in AEOS. The resulting pale yellow, transparent solution is dropped onto untreated PC sheets, ensuring a dry weight of 400 g / m². 2 Test samples were prepared by curing at 60°C for 4 hours and then at 80°C for 24 hours in a constant temperature drying oven.

[0037] Example 2

[0038] Accurately weigh 3.85g of DPTEPA and 12.15g of AEOS and dissolve them in 30ml of a 1:1 mixture of ethanol and acetonitrile to prepare DPTEPA. 0.75 -AEOS1 coating solution, where 0.75 represents the ratio of reactive H in DPTEPA to the number of epoxy groups in AEOS. The resulting pale yellow, transparent solution is dropped onto untreated PC sheets, ensuring a dry weight of 400 g / m². 2 Test samples were prepared by curing at 60°C for 4 hours and then at 80°C for 24 hours in a constant temperature drying oven.

[0039] Example 3

[0040] Accurately weigh 4.75g of DPTEPA and 11.25g of AEOS and dissolve them in 30ml of a 1:1 mixture of ethanol and acetonitrile to prepare the DPTEPA1-AEOS1 coating solution, where 1 represents the ratio of the active hydrogen atoms in DPTEPA to the number of epoxy groups in AEOS. Add the resulting pale yellow transparent solution dropwise onto untreated PC sheets, ensuring a dry weight of 400g / m². 2 Test samples were prepared by curing at 60°C for 4 hours and then at 80°C for 24 hours in a constant temperature drying oven.

[0041] Example 4

[0042] Accurately weigh 5.53g of DPTEPA and 10.47g of AEOS and dissolve them in 30ml of a 1:1 mixture of ethanol and acetonitrile to prepare DPTEPA. 1.25 -AEOS1 coating solution, where 1.25 represents the ratio of reactive H in DPTEPA to the number of epoxy groups in AEOS. The resulting pale yellow, transparent solution is dropped onto untreated PC sheets, ensuring a dry weight of 400 g / m². 2 Test samples were prepared by curing at 60°C for 4 hours and then at 80°C for 24 hours in a constant temperature drying oven.

[0043] Example 5

[0044] Accurately weigh 6.21g of DPTEPA and 9.79g of AEOS and dissolve them in 30ml of a 1:1 mixture of ethanol and acetonitrile to prepare DPTEPA. 1.5-AEOS1 coating solution, where 1.5 represents the ratio of reactive H in DPTEPA to the number of epoxy groups in AEOS. The resulting pale yellow, transparent solution is dropped onto untreated PC sheets, ensuring a dry weight of 400 g / m². 2 Test samples were prepared by curing at 60°C for 4 hours and then at 80°C for 24 hours in a constant temperature drying oven.

[0045] Table 1 Formulations of Examples 1-5

[0046] Samples DPTEPA AEOS EthylAlcohol Acetonitrile <![CDATA[DPTEPA 0.5 -AEOS1]]> 2.79g 13.21g 15ml 15ml <![CDATA[DPTEPA 0.75 -AEOS1]]> 3.85g 12.15g 15ml 15ml <![CDATA[DPTEPA1-AEOS1]]> 4.75g 11.25g 15ml 15ml <![CDATA[DPTEPA 1.25 -AEOS1]]> 5.53g 10.47g 15ml 15ml <![CDATA[DPTEPA1 .5 -AEOS1]]> 6.21g 9.79g 15ml 15ml

[0047] Table 2. Test results of coating adhesion, pencil hardness, and water contact angle.

[0048]

[0049]

[0050] like Figure 5 As shown in Figure a, the infrared spectrum of tetraethylenepentamine (TEPA) is at 3363 cm⁻¹. -1 and 3280cm -1 The characteristic doublet of -NH2 appeared at 3214 cm⁻¹, while the doublet disappeared in the synthetic product DPTEPA. -1 The -NH characteristic peak appears at [location], combined with [other factors]. Figure 5 The NMR spectrum in bc confirms the successful synthesis of DPTEPA. Figure 5 As shown in d, AEOS is at 908cm -1 The coatings exhibit infrared characteristic absorption peaks at 3412 cm⁻¹, with five different formulations showing peaks at this location. -1 A broad hydroxyl absorption peak appeared at 908 cm⁻¹, and the epoxy group showed a peak at 908 cm⁻¹. -1 The disappearance of the characteristic peak at this point indicates that AEOS and DPTEPA underwent ring-opening polymerization. For example... Figure 5 As shown in e, AEOS 29 The Si NMR spectrum exhibits a broad peak between -65 and -70 ppm, corresponding to T 3 The [R-Si(OSi)3] peak confirms the successful synthesis of AEOS. Figure 5 As shown in f, DPTEPA is applied. 1.25 - The PC substrate with the AEOS1 coating has a smooth surface and uniform distribution of C, N, O, Si, and P elements.

[0051] like Figure 6 As shown in ab, the coating surface is slightly yellowed, and within the wavelength range of 400-600nm, the transmittance decreases with increasing DPTEPA content. Figure 6 cd and as shown in Table 2, DPTEPA was applied. 1.25- The AEOS1 coating has an adhesion rating of 3B and a hydrophobic angle of 87.938°.

[0052] like Figure 7 As shown in ab, with the increase of DPTEPA content, the pyrolysis phenomenon occurs earlier, indicating that the coating can react faster to produce a dense carbon layer when exposed to flame erosion, protecting the internal substrate from erosion. Correspondingly, the decrease in Si content will lead to a decrease in the residual carbon rate.

[0053] like Figure 8 As shown, in the initial stage of combustion, the coating rapidly carbonizes into a dense char layer, blocking the erosion of the PC substrate by heat radiation, thus enabling the coating of DPTEPA to withstand the erosion. 1.25 - The PHRR value of PC sheets with AEOS1 coating was reduced by 43.59%.

[0054] like Figure 9 As shown, the density of the carbon layer is improved with the increase of DPTEPA content.

[0055] like Figure 10 As shown in a, it is DPTEPA 1.25 -The FTIR spectrum of the AEOS1 coating during pyrolysis shows the appearance of PO (949 cm⁻¹) at around 370℃. -1 Characteristic peaks appeared after 350℃, with NH (912 cm⁻¹) appearing. -1 ) and PNH (3015cm -1 Characteristic peaks. These phosphorylated fragments can be converted into PO· radicals, which can capture H· and HO· radicals during combustion, thereby terminating the combustion reaction. The presence of NH groups indicates the generation of NH3 and its derivatives, which dilute combustible gases during combustion. Based on the radical-capturing effect and the dilution effect on combustible gases, DPTEPA... 1.25 - The AEOS1 coating provides vapor-phase flame retardancy. For example... Figure 10 As shown in b, the FTIR spectrum analysis of the residual char indicates that the DPTEPA-AEOS coating composite can produce a char layer containing P and Si-O-Si structures. This char layer can block heat exchange between the external environment and the internal matrix, thus playing a role in condensed phase flame retardancy. Figure 10 As shown in c, DPTEPA 1.25 - The AEOS1 solution was poured into a polytetrafluoroethylene mold and cured into a sample for vertical burning test. The coated sample self-extinguished when removed from the open flame, and the flame retardant rating can reach V-0.

Claims

1. A compound for use in transparent flame-retardant coatings, characterized in that: The structural formula of the compound is shown below: ； The preparation method includes the following steps: (1) Weigh out tetraethylenepentamine TEPA and dissolve it in an organic solvent. At the same time, add anhydrous K2CO3 and stir mechanically. Place it in an ice-water bath environment for later use. Dissolve diphenylphosphine chloride DPPC in an organic solvent and add it dropwise to the TEPA solution under N2 atmosphere. After the addition is complete, continue stirring at room temperature. After the reaction is complete, the product 1,11-bis[(oxoylidediphenyl-λ5-methylphospho)amino]-3,6,9-triazaundecaneDPTEPA is obtained through post-treatment. (2) The DPTEPA and ladder-shaped epoxy polysiloxane AEOS obtained above are dissolved in a mixed solution of ethanol and acetonitrile to obtain a transparent flame-retardant coating compound; the preparation method of AEOS includes the following steps: γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH560 is reacted at room temperature under the conditions of THF and anhydrous K2CO3, and the ladder-shaped epoxy polysiloxane AEOS is obtained after post-treatment.

2. A method for preparing a transparent flame-retardant coating compound, comprising the following steps: (1) Weigh out tetraethylenepentamine TEPA and dissolve it in an organic solvent. At the same time, add anhydrous K2CO3 and stir mechanically. Place it in an ice-water bath environment for later use. Dissolve diphenylphosphine chloride DPPC in an organic solvent and add it dropwise to the TEPA solution under N2 atmosphere. After the addition is complete, continue stirring at room temperature. After the reaction is complete, the product 1,11-bis[(oxoylidediphenyl-λ5-methylphospho)amino]-3,6,9-triazaundecaneDPTEPA is obtained through post-treatment. (2) The DPTEPA and ladder-shaped epoxy polysiloxane AEOS obtained above are dissolved in a mixed solution of ethanol and acetonitrile to obtain a transparent flame-retardant coating compound; the preparation method of AEOS includes the following steps: γ-(2,3-epoxypropoxy)propyltrimethoxysilane KH560 is reacted at room temperature under the conditions of THF and anhydrous K2CO3, and the ladder-shaped epoxy polysiloxane AEOS is obtained after post-treatment.

3. The preparation method according to claim 2, characterized in that: The molar ratio of TEPA to DPPC in step (1) is 1:1.5-2.

5.

4. The preparation method according to claim 2, characterized in that: The concentration of the TEPA solution in step (1) is (5-6) × 10 -4 mol / L; DPPC solution concentration is (1-2)×10 -3 mol / L.

5. The preparation method according to claim 2, characterized in that: The organic solvent in step (1) is dichloromethane.

6. The preparation method according to claim 2, characterized in that: The molar ratio of anhydrous K2CO3 to TEPA in step (1) is 1:0.4-0.

8.

7. The preparation method according to claim 2, characterized in that: The molar ratio of DPTEPA to AEOS in step (2) is 0.5-1.5:

1.

8. The preparation method according to claim 2, characterized in that: In step (2), the volume ratio of ethanol to acetonitrile in the ethanol-acetonitrile mixed solution is 1:

1.

9. The use of a transparent flame-retardant coating compound as described in claim 1 in the flame-retardant treatment of polycarbonate.

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