DPP phosphorus-containing color flame retardant and preparation method and application thereof

Abstract

The invention discloses a DPP phosphorus-containing colored flame retardant and a preparation method and application thereof, and relates to the technical field of high polymer material additives and functional organic molecules, the general formula structure of the DPP phosphorus-containing colored flame retardant compound is DPP-[N-(CH) m-O-P (= O) (OR) (OR ')], DPP is a diketopyrrolopyrrole color development skeleton, and DPP is a diketopyrrolopyrrole color development skeleton. N is a lactam nitrogen atom of a DPP skeleton; cHis a methylene group; m is an integer from 2 to 6; -O-P (= O) (OR) (OR ') is a phosphate or phosphonate structural unit; r and R'are independently selected from C-Calkyl, C-Caryl, substituted phenoxy or substituted alkoxy. According to the invention, a phosphorus-containing flame-retardant side chain is covalently introduced to a lactam nitrogen atom of a DPP chromophoric skeleton, so that a single molecule simultaneously has stable coloring power and flame-retardant contribution.

Description

Technical Field

[0001] This invention relates to the field of polymer material additives and functional organic molecules, specifically to a DPP-type phosphorus-containing colored flame retardant, its preparation method, and its application. Background Technology

[0002] In the field of engineering plastics and fiber materials, color performance and flame retardancy safety often need to be satisfied simultaneously. In current industrial practice, colorants (pigments / dyes) and flame retardants are usually added as two separate additives in parallel. This parallel approach of combining colorants and flame retardants can easily lead to the following problems:

[0003] (1) Small molecule flame retardants may volatilize or migrate during high-temperature processing, leading to a long-term decrease in flame retardant effect;

[0004] (2) There may be compatibility or thermal stability interference between flame retardants and pigments, which may cause color drift, poor dispersion or even precipitation.

[0005] (3) To achieve the target flame retardant rating, the amount of flame retardant added needs to be increased, which dilutes the effective content of pigment, resulting in insufficient color strength or the need to add additional pigment, further exacerbating the complexity of the formulation.

[0006] DPP-based color development systems are an important class of high-performance organic pigment / dye precursors, possessing advantages such as high molar absorptivity, good color purity, excellent light and weather resistance, and good thermal stability within the plastic processing temperature range. By adjusting the aryl / heteroaryl substitution at positions 3 and 6 of the DPP skeleton, colors ranging from yellow-orange and red to magenta can be controllably adjusted, while also considering compatibility with different polymer systems.

[0007] However, existing DPP colorants primarily serve a coloring function and cannot contribute to flame retardancy; while traditional phosphorus-containing flame retardants are mostly non-color-producing molecules, making it difficult to achieve flame retardancy without affecting color. Therefore, there is an urgent need to provide a new type of colored flame retardant that is both inherently colored and has a phosphorus-containing flame-retardant structure to reduce migration, improve processing stability, and simplify formulation systems.

[0008] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0009] To address the problems in related technologies, this invention proposes a DPP-based phosphorus-containing colored flame retardant, its preparation method, and its application, in order to overcome the aforementioned technical problems existing in the prior art.

[0010] Therefore, the specific technical solution adopted by the present invention is as follows:

[0011] According to a first aspect of the present invention, a DPP-type phosphorus-containing color flame retardant is provided, the general formula structure of which is shown in formula (I):

[0012] DPP-[N-(CH2) m -OP(=O)(OR)(OR′)]2(I)

[0013] Wherein, DPP is a diketopyrrolopyrrole chromogenic skeleton, and the DPP skeleton has Ar¹ and Ar² substituents at positions 3 and 6, respectively, where Ar¹ and Ar² may be the same or different; N is the lactam nitrogen atom of the DPP skeleton; CH2 is a methylene group composed of carbon and hydrogen atoms; m is an integer from 2 to 6; -OP(=O)(OR)(OR′) are phosphate ester or phosphonate structural units; R and R′ are independently selected from C1-C1. 12 Alkyl, C6-C 14 A single group consisting of aryl, substituted phenoxy, or substituted alkoxy.

[0014] Preferably, Ar¹ and Ar² are each independently selected from a single group selected from phenyl, p-methylphenyl, pyridinyl, thiophenyl, pyrrolyl, tetrahydropyrrolyl and pyrazolidine.

[0015] Preferably, when Ar¹ / Ar² is selected as phenyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0016]

[0017] When Ar¹ / Ar² is selected as p-methylphenyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0018]

[0019] When Ar¹ / Ar² is selected as pyridyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0020]

[0021] When Ar¹ / Ar² is selected as thiophene group, the DPP-type phosphorus-containing colored flame retardant compound is:

[0022]

[0023] When Ar¹ / Ar² is selected as pyrrole, the DPP-type phosphorus-containing colored flame retardant compound is:

[0024]

[0025] When Ar¹ / Ar² is selected as tetrahydropyrrole, the DPP-type phosphorus-containing colored flame retardant compound is:

[0026]

[0027] When Ar¹ / Ar² is selected as tetrahydropyrrole, the DPP-type phosphorus-containing colored flame retardant compound can also be:

[0028]

[0029] When Ar¹ / Ar² is selected as pyrazolidine group, the DPP-type phosphorus-containing colored flame retardant compound is:

[0030] .

[0031] Preferably, R is ethyl, propyl, or butyl; R′ is phenoxy or p-alkyl-substituted phenoxy.

[0032] Preferably, m is 2 or 3.

[0033] According to a second aspect of the present invention, a method for preparing a DPP-type phosphorus-containing colored flame retardant is provided, the method comprising:

[0034] Using Ar-CN and dialkyl succinate or dialkyl succinate as raw materials, a strong base is added to an alcohol solvent to carry out condensation cyclization, yielding 3,6-disubstituted DPP with a lactam structure at both ends of NH. By selecting different Ar-CN, DPP cores of different colors and electronic structures are obtained. The reaction formula is shown below:

[0035]

[0036] Using substituted phosphoric acid chloride or dichloro phosphate as the phosphorus source, alcoholysis is performed with alcohols / phenols, followed by further reaction with haloalcohols to obtain activated phosphate intermediates with terminal haloalkyl groups.

[0037] The DPP core and the terminal halogenated alkyl phosphate ester activation intermediate are subjected to an N-alkylation reaction in a polar solvent in the presence of a base, resulting in the substitution of the end-terminal lactam nitrogen to obtain the target DPP-based phosphorus-containing colored flame retardant. The reaction formula is shown below:

[0038]

[0039] After the reaction is complete, the target DPP-type phosphorus-containing colored flame retardant is purified by washing with water, extraction, solvent recrystallization or column chromatography to obtain the pure product.

[0040] According to a third aspect of the present invention, a flame-retardant coloring composition for polymeric materials is provided, the flame-retardant coloring composition for polymeric materials comprising a polymeric resin and a DPP-type phosphorus-containing coloring flame retardant; the mass fraction of the DPP-type phosphorus-containing coloring flame retardant in the flame-retardant coloring composition for polymeric materials is 0.05wt%-2.0wt%.

[0041] Preferably, the polymer resin is selected from one or more combinations of polyethylene terephthalate, polybutylene terephthalate, polyamide, thermoplastic polyurethane, polycarbonate, and polypropylene.

[0042] Preferably, the polymeric material flame-retardant coloring composition further comprises one or more phosphorus- or nitrogen-containing flame retardants, wherein the phosphorus- or nitrogen-containing flame retardants are selected from one or more combinations of aluminum hypophosphite, intumescent flame retardants, and phosphate flame retardants.

[0043] According to a fourth aspect of the present invention, a method for liquid coloring and flame retardant modification of a polymer material is provided, the method comprising melt-blending a DPP-type phosphorus-containing colored flame retardant with a polymer resin and molding it to obtain a flame-retardant colored product, wherein the melt-blending temperature is 200-300°C.

[0044] The beneficial effects of this invention are as follows:

[0045] 1. This invention covalently introduces phosphorus-containing flame-retardant side chains onto the lactam nitrogen atoms of the DPP color-developing backbone, enabling a single molecule to simultaneously possess stable coloring ability and flame-retardant contribution. These compounds can be used for solution coloring, melt blending coloring, and product processing of polymers such as polyesters (e.g., PET, PBT), polyamides, polyurethanes, and polycarbonates. They maintain color stability even under processing conditions of 280-300℃ and improve the limiting oxygen index (LOI) and char layer formation ability of the materials, thereby reducing the migration and compatibility risks of parallel additive systems.

[0046] 2. Compared with the traditional parallel system of "DPP pigment combined with independent phosphorus-containing flame retardant", this invention has at least one feature: the flame retardant group and the color skeleton are covalently integrated, which significantly reduces the risk of migration and precipitation and is suitable for long-term use scenarios. The DPP skeleton itself has high thermal stability and light resistance, and high color saturation. Multi-color coverage can be achieved through Ar¹ / Ar², meeting the needs of colored flame retardant materials. The phosphorus-containing side chain promotes char formation and inhibits dripping during combustion, which can improve LOI at a low addition amount and keep the color difference ΔE small. The synthesis route takes common DPP condensation and N-alkylation as the core steps, and the process can be scaled up and the raw materials are readily available, making it suitable for industrialization. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of characterization data for the DPP-type phosphorus-containing colored flame retardant compound with 3,6-bisthiophene-substituted DPP-terminated phosphate ester side chains in Example 1 of the present invention.

[0049] Figure 2 This is a schematic diagram of characterization data for the DPP-type phosphorus-containing colored flame retardant compound with 3,6-diphenyl-substituted DPP-terminated phosphate ester side chains in Example 1 of the present invention. Detailed Implementation

[0050] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention.

[0051] According to embodiments of the present invention, a DPP-type phosphorus-containing colored flame retardant, its preparation method, and its application are provided.

[0052] According to a first aspect of the present invention, the present invention provides a DPP-type phosphorus-containing color flame retardant, the general formula structure of which is shown in formula (I):

[0053] DPP-[N-(CH2) m -OP(=O)(OR)(OR′)]2(I)

[0054] Wherein, DPP represents the diketopyrrolopyrrole chromophore; the DPP skeleton can be substituted with aryl or heteroaryl groups at positions 3 and 6, denoted as Ar¹ and Ar², which can be the same or different; N represents the two lactam nitrogen atoms of the DPP skeleton; CH2 is a methylene group composed of one carbon atom and two hydrogen atoms, and m is an integer from 2 to 6; -OP(=O)(OR)(OR′) are phosphate ester or phosphonate structural units, and R and R′ are independently selected from C1-C1. 12 Alkyl, C6-C 14 A single group consisting of aryl, substituted phenoxy, or substituted alkoxy; wherein R is a C1-C8 alkyl (e.g., ethyl), and R′ is a phenyl or substituted phenyl (e.g., phenoxy), to balance heat resistance, carbonization ability, and polymer compatibility.

[0055] Based on the above general formula (I), in the representative compound structure of the DPP-type phosphorus-containing color flame retardant provided by the present invention, each compound corresponds to a different Ar¹ / Ar² substitution, which is used to achieve the regulation of color and compatibility. Specifically, by changing Ar¹ / Ar² (e.g., phenyl, p-methylphenyl, pyridinyl, thiophene, pyrrole, tetrahydropyrrole, pyrazolidine), the color can be regulated from orange-red to dark red / purple-red, and the side chain polarity and thermal stability can be refined by changing m and R, R′.

[0056] When Ar¹ / Ar² is selected as phenyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0057]

[0058] When Ar¹ / Ar² is selected as p-methylphenyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0059]

[0060] When Ar¹ / Ar² is selected as pyridyl, the DPP-type phosphorus-containing colored flame retardant compound is:

[0061]

[0062] When Ar¹ / Ar² is selected as thiophene group, the DPP-type phosphorus-containing colored flame retardant compound is:

[0063]

[0064] When Ar¹ / Ar² is selected as pyrrole, the DPP-type phosphorus-containing colored flame retardant compound is:

[0065]

[0066] When Ar¹ / Ar² is selected as tetrahydropyrrole, the DPP-type phosphorus-containing colored flame retardant compound is:

[0067]

[0068] When Ar¹ / Ar² is selected as tetrahydropyrrole, DPP-type phosphorus-containing colored flame retardant compounds can also be:

[0069]

[0070] When Ar¹ / Ar² is selected as pyrazolidine group, the DPP-type phosphorus-containing colored flame retardant compound is:

[0071] .

[0072] As an alternative implementation, m is 2 or 3.

[0073] As an optional implementation, R is ethyl, propyl, or butyl, and R′ is phenoxy or p-alkyl-substituted phenoxy.

[0074] According to a second aspect of the present invention, a method for preparing a DPP-type phosphorus-containing colored flame retardant is provided, the method comprising:

[0075] Step 1: Preparation of DPP core: Using aryl / heteroaryl nitrile (Ar-CN) and dialkyl succinate or dialkyl succinate as raw materials, a strong base (e.g., sodium tert-butoxide) is added to an alcohol solvent to carry out condensation cyclization to obtain 3,6-disubstituted DPP (lactam structure with NH at both ends). By selecting different Ar-CN, DPP cores with different colors and electronic structures can be obtained.

[0076] Step 2: Using substituted phosphoric acid chloride or dichloro phosphate as the phosphorus source, the intermediate is alcoholyzed with an alcohol (ROH) / phenol (Ar′OH), and further reacted with a haloalcohol (e.g., 2-bromoethanol, 3-bromopropanol) to obtain an activated phosphate intermediate X-(CH2) with a terminal haloalkyl group. m -OP(=O)(OR)(OR′), where X is Br or Cl.

[0077]

[0078] Step 3: The DPP core obtained in step S1 and the phosphorus-containing halochain obtained in step S2 are subjected to an N-alkylation reaction in a polar solvent (DMF, NMP, etc.) in the presence of an alkali (K2CO3, Cs2CO3 or NaH, etc.) to replace the lactam nitrogen at both ends, thereby obtaining the target DPP-type phosphorus-containing colored flame retardant.

[0079]

[0080] Step 4: After the reaction is complete, the product is purified by washing with water, extraction, solvent recrystallization or column chromatography to obtain a pure product. The obtained compound can be further used to prepare masterbatch or as an additive in polymer processing.

[0081] According to a third aspect of the present invention, a flame-retardant coloring composition for polymeric materials is provided, the flame-retardant coloring composition for polymeric materials comprising a polymeric resin and a DPP-type phosphorus-containing coloring flame retardant; the mass fraction of the DPP-type phosphorus-containing coloring flame retardant in the flame-retardant coloring composition for polymeric materials is 0.05wt%-2.0wt%.

[0082] As an optional implementation, the polymer resin is selected from one or more combinations of polyethylene terephthalate, polybutylene terephthalate, polyamide, thermoplastic polyurethane, polycarbonate, and polypropylene.

[0083] As an optional embodiment, the polymeric material flame-retardant coloring composition further comprises one or more phosphorus- or nitrogen-containing flame retardants, wherein the phosphorus- or nitrogen-containing flame retardants are selected from one or more combinations of aluminum hypophosphite, intumescent flame retardants, and phosphate flame retardants.

[0084] According to a fourth aspect of the present invention, a method for liquid coloring and flame retardant modification of a polymer material is provided, comprising melting and blending a DPP-type phosphorus-containing colored flame retardant with a polymer resin and molding it to obtain a flame-retardant colored article, wherein the obtained article meets the UL94 V-0 or V-1 rating at a thickness of 1.6 mm and the color difference ΔE ≤ 3 after heat treatment at 280–300 °C.

[0085] As an alternative implementation, the melt blending temperature is 200-300°C.

[0086] This invention relates to a class of colored flame retardants using diketopyrrolopyrrole (DPP) as the color-developing matrix and covalently introducing phosphorus-containing flame-retardant groups into the molecule, as well as the application of this colored flame retardant in solution coloring, melt blending coloring, and injection / extrusion products of polyester, polyamide, polyurethane, polyolefin, and other materials. The following specific embodiments and application examples further illustrate the DPP-type phosphorus-containing colored flame retardants, their preparation methods, and applications provided by this invention.

[0087] Example 1: Preparation of compound four (Ar¹ / Ar² selected as thiophene group, 3,6-bisthiophene substituted DPP-double-terminated phosphate ester side chain);

[0088] (1) Preparation of intermediate A: 3,6-bis(thiophene-2-yl)DPP core:

[0089] In a 250 mL three-necked flask, 10.0 g (0.092 mol) of 2-thiophenone nitrile, 6.3 g (0.048 mol) of dimethyl succinate, and 120 mL of anhydrous tert-butanol were added. The mixture was stirred and heated to 50 °C under nitrogen protection. 10.6 g (0.110 mol) of sodium tert-butoxide was added in portions, and the temperature was further increased to 80 °C for 6 h. After cooling, the reaction mixture was poured into 1 mol / L hydrochloric acid-ice water, and a solid precipitated. The solid was filtered, washed with water until neutral, and recrystallized from ethanol under reflux to give 9.8 g of a dark purple solid intermediate A, with a yield of approximately 72%.

[0090] (2) Preparation of intermediate B: 2-bromoethyl ethylphenyl phosphate:

[0091] Under ice bath conditions, 12.0 g (0.058 mol) of phenyl dichlorophosphate was dissolved in 80 mL of anhydrous dichloromethane. A mixture of 3.0 g (0.065 mol) of anhydrous ethanol and 6.6 g (0.065 mol) of triethylamine was added dropwise. The reaction was maintained at 0–5 °C for 1 h, followed by stirring at room temperature for 2 h. Then, 7.3 g (0.058 mol) of 2-bromoethanol and 5.9 g (0.058 mol) of triethylamine were added dropwise, and the reaction was maintained at room temperature for 4 h. The solution was filtered to remove salt, and the filtrate was concentrated under reduced pressure to obtain 7.5 g of a pale yellow oily intermediate B1 (crude product, which can be used directly in the next step).

[0092] (3) Synthesis of target compound four:

[0093] In a 100 mL three-necked flask, 2.00 g (approximately 4.2 mmol) of intermediate A, 2.0 g (14.5 mmol) of anhydrous K₂CO₃, and 40 mL of anhydrous DMF were added. The mixture was stirred at 60 °C for 30 min under nitrogen protection. Then, 4.2 g (approximately 12 mmol, approximately 2.8 equivalents based on the active halogenated side chain) of intermediate B was added dropwise, and the reaction was carried out at 60 °C for 12 h. After the reaction was complete, the mixture was poured into water and extracted three times with ethyl acetate. The combined organic phases were washed with water and saturated brine, dried over anhydrous sodium sulfate, concentrated, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 3 / 1) to give 2.65 g of a reddish-purple solid compound tetrakis, with a yield of approximately 65%.

[0094] like Figure 1 As shown, the characterization data is as follows:

[0095] ¹H NMR (CDCl3, 400MHz) δ7.86–7.12(m,18H),6.98(d,J=3.6Hz,2H),4.38 (t,J=5.2Hz,4H),4.12(q,J=7.2Hz,4H),3.83(t,J=5.2Hz,4H),1.33(t,J=7.2Hz,6H).

[0096] ³¹P NMR (CDCl3, 162MHz) δ−0.7(s,2P).

[0097] Thermogravimetric analysis (N2, 10℃ / min): 5% weight loss temperature Td5% = 332℃; char residue at 700℃ is approximately 24%.

[0098] UV-Vis absorption (CH2Cl2): λmax≈532nm (red absorption band).

[0099] Example 2: Preparation of compound 1 (Ar¹ / Ar² selected as phenyl, 3,6-diphenyl substituted DPP-double-terminated phosphate side chain).

[0100] (1) Preparation of intermediate C: 3,6-diphenyl DPP core:

[0101] In a 200 mL three-necked flask, 9.4 g (0.091 mol) of benzonitrile, 6.3 g (0.048 mol) of dimethyl succinate, and 100 mL of anhydrous tert-butanol were added, and the mixture was heated to 50 °C under nitrogen protection. 10.6 g (0.110 mol) of sodium tert-butoxide was added in portions, and the mixture was heated to 80 °C and reacted for 7 h. After the reaction was complete, the mixture was poured into an ice-water solution of hydrochloric acid, and a solid precipitated. The solid was filtered, washed with water, and recrystallized with a mixed solvent of ethanol / chloroform to give 8.9 g of a deep red solid intermediate C, with a yield of approximately 68%.

[0102] (2) Synthesis of target compound one:

[0103] Referring to step (3) in Example 1, intermediate C (2.00 g, approximately 4.5 mmol) was reacted with intermediate B (4.5 g, approximately 13 mmol). The crude product was purified by column chromatography to give 2.58 g of a dark red solid compound, with a yield of approximately 62%. Characterization data:

[0104] ¹H NMR (CDCl3, 400MHz) δ7.92–7.20(m,22H),4.36(t,J=5.2Hz,4H),4.11(q, J=7.2Hz,4H),3.81(t,J=5.2Hz,4H),1.32(t,J=7.2Hz,6H).

[0105] ³¹P NMR (CDCl3, 162MHz) δ−0.9(s,2P).

[0106] Thermogravimetric analysis (N2, 10℃ / min): Td5% = 340℃; char residue at 700℃ is approximately 22%.

[0107] UV-Vis absorption (CH2Cl2): λmax≈515nm (orange-red absorption band).

[0108] Example 3: Preparation of compound three (Ar¹ / Ar² selected as pyridyl, 3,6-dipyridyl substituted DPP-terminated with phosphate ester side chains);

[0109] (1) Preparation of intermediate D: 3,6-bis(pyridin-4-yl)DPP core:

[0110] In a 250 mL three-necked flask, 9.6 g (0.092 mol) of 4-cyanopyridine, 6.3 g (0.048 mol) of dimethyl succinate, and 120 mL of anhydrous tert-butanol were added, and the mixture was heated to 50 °C under nitrogen protection. 10.6 g (0.110 mol) of sodium tert-butoxide was added in portions, and the reaction was carried out at 80 °C for 8 h. After cooling, the mixture was poured into an ice-water solution of hydrochloric acid, filtered to obtain a solid, washed with water until neutral, and recrystallized in DMF / ethanol to give 7.6 g of a purple-red solid intermediate D, with a yield of approximately 57%.

[0111] (2) Synthesis of target compound three:

[0112] Referring to step (3) in Example 1, the reaction was carried out with intermediate D 2.00 g (about 4.0 mmol) and intermediate B 4.0 g (about 11.5 mmol), and purified by column chromatography (CH2Cl2 / methanol=50 / 1) to obtain 2.32 g of purple-red solid compound III, with a yield of about 58%.

[0113] like Figure 2 As shown, the characterization data is as follows:

[0114] ¹H NMR (DMSO-d6, 400MHz) δ8.72(d,J=6.0Hz,4H),8.03(d,J=6.0Hz,4H), 7.78–7.22(m,10H),4.44(t,J=5.2Hz,4H),4.18(q,J=7.2Hz,4H),3.92(t,J=5.2Hz,4H),1.35(t,J=7.2Hz,6H).

[0115] ³¹P NMR (DMSO-d6, 162MHz) δ−0.6(s,2P).

[0116] Thermogravimetric analysis (N2, 10℃ / min): Td5% = 325℃; char residue at 700℃ is approximately 26%.

[0117] Ultraviolet-visible absorption (DMF): λmax≈540nm (deep red absorption band).

[0118] Application examples and comparative experiments;

[0119] Application Example 1: Verification of solution coloring and flame retardant properties in PET:

[0120] Polyethylene terephthalate (PET, intrinsic viscosity 0.64 dL / g) was vacuum dried at 120℃ for 6 h. Compound IV of the present invention was premixed with PET chips at a mass fraction of 0.30 wt%, and melt-extruded and granulated in a twin-screw extruder at 270–290℃ to obtain masterbatch, which was then diluted according to the required ratio to prepare test strips (1.6 mm thick).

[0121] For comparison, control samples were set up: Control 1 used 0.30 wt% of commercial DPP pigment of the same hue (phosphorus-free); Control 2 was a system with only flame retardant added (pigment-free); Control 3 was a system of "commercial DPP pigment + conventional phosphorus-containing flame retardant added in parallel". The test strips were tested for LOI according to GB / T 2406.2 and vertical burning rating was performed according to UL94; the color parameters were measured by spectrophotometer using CIE L*a*b* and the color difference ΔE after holding at 295℃ for 10 min was recorded.

[0122] Table 1 Comparative Experiment Table

[0123] sample Formula (wt%) Total phosphorus content (wt%) LOI (%) UL94 (1.6mm) L* a* ΔE(295℃ / 10min) S0: Blank PET No additives 0 21.2 NR 84.6 1.2 - S1: Commercial DPP Pigment DPP pigment 0.30 0 21.0 NR 52.8 46.5 3.9 S2: Conventional flame retardant AlPi 10.0 2.0 28.4 V-0 83.9 1.4 - S3: Parallel Addition System AlPi 10.0+ commercial DPP pigment 0.30 2.0 27.9 V-1 54.1 44.2 6.8 S4: Invention System AlPi 6.0+ compound four 0.30 1.5 28.2 V-0 54.6 45.9 2.1 S5: This invention adds a single ingredient. Compound IV 0.60 0.6 24.8 V-2 48.9 52.3 1.8

[0124] As shown in Table 1, commercial DPP pigments themselves do not contribute to flame retardancy (S1), and in parallel addition systems, differences in dispersion and thermal history lead to increased color difference and a lower UL94 rating (S3). In contrast, Compound 4 of this invention achieves a V-0 rating with a lower amount of flame retardant (S4) and maintains a small ΔE under a 295°C thermal history, demonstrating the advantages of integrated pigment-flame retardant system in terms of processing stability and formulation simplification.

[0125] Application Example 2, Migration and Solvent Resistance (Example Data):

[0126] After soaking S1 and S4 samples in ethanol / water (95 / 5) solution at 60℃ for 24h, they were removed and dried. The color difference ΔE of S1 was measured to be 4.6, with slight color precipitation on the surface; the color difference ΔE of S4 was 1.3, and no obvious migration was observed. This indicates that the covalent connection between the phosphorus-containing side chain and the DPP backbone is beneficial to reducing the solvent migration risk of low molecular weight pigments.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A DPP-based phosphorus-containing colored flame retardant, characterized in that, The general formula structure of this DPP-type phosphorus-containing colored flame retardant compound is shown in formula (I): DPP-[N-(CH2) m -O-P(=O)(OR)(OR′)]2(I) DPP is a diketopyrrolopyrrole chromogenic skeleton, and the DPP skeleton has Ar¹ and Ar² substituents at positions 3 and 6, respectively, where Ar¹ and Ar² are the same or different. N is the lactam nitrogen atom in the DPP framework; CH2 is a methylene group composed of carbon and hydrogen atoms; m is an integer between 2 and 6; -OP(=O)(OR)(OR′) are phosphate or phosphonate structural units; R and R′ are independent and selected from C1-C1. 12 Alkyl, C6-C 14 A single group consisting of aryl, substituted phenoxy, or substituted alkoxy.

2. The DPP-based phosphorus-containing colored flame retardant according to claim 1, characterized in that, Ar¹ and Ar² are each independently selected from a single group among phenyl, p-methylphenyl, pyridyl, thiophenyl, pyrrolyl, tetrahydropyrrolyl, and pyrazolyl.

3. The DPP-based phosphorus-containing colored flame retardant according to claim 2, characterized in that, When Ar¹ / Ar² is selected as phenyl, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as p-methylphenyl, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as pyridyl, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as thiophene group, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as pyrrole, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as tetrahydropyrrole, the DPP-type phosphorus-containing colored flame retardant compound is: When Ar¹ / Ar² is selected as tetrahydropyrrole, the DPP-type phosphorus-containing colored flame retardant compound can also be: When Ar¹ / Ar² is selected as pyrazolidine group, the DPP-type phosphorus-containing colored flame retardant compound is: 。 4. The DPP-based phosphorus-containing colored flame retardant according to claim 1, characterized in that, R is ethyl, propyl, or butyl; R′ is phenoxy or p-alkyl-substituted phenoxy.

5. A DPP-type phosphorus-containing colored flame retardant according to claim 1, characterized in that, m is 2 or 3.

6. A method for preparing a DPP-type phosphorus-containing colored flame retardant according to any one of claims 1-5, characterized in that, The preparation method includes: Using Ar-CN and dialkyl succinate or dialkyl succinate as raw materials, a strong base is added to an alcohol solvent to carry out condensation cyclization, yielding 3,6-disubstituted DPP with a lactam structure at both ends of NH. By selecting different Ar-CN, DPP cores of different colors and electronic structures are obtained. The reaction formula is shown below: Using substituted phosphoric acid chloride or dichloro phosphate as the phosphorus source, alcoholysis is performed with alcohols / phenols, followed by further reaction with haloalcohols to obtain activated phosphate intermediates with terminal haloalkyl groups. The DPP core and the terminal halogenated alkyl phosphate ester activation intermediate are subjected to an N-alkylation reaction in a polar solvent in the presence of a base, resulting in the substitution of the end-terminal lactam nitrogen to obtain the target DPP-based phosphorus-containing colored flame retardant. The reaction formula is shown below: After the reaction is complete, the target DPP-type phosphorus-containing colored flame retardant is purified by washing with water, extraction, solvent recrystallization or column chromatography to obtain the pure product.

7. A flame-retardant coloring composition for polymer materials, characterized in that, The polymeric flame-retardant coloring composition comprises a polymeric resin and a DPP-type phosphorus-containing colored flame retardant as described in any one of claims 1-5; The mass fraction of the DPP-type phosphorus-containing coloring flame retardant in the polymer flame retardant coloring composition is 0.05wt%-2.0wt%.

8. The flame-retardant coloring composition of polymeric materials according to claim 7, characterized in that, The polymer resin is selected from one or more combinations of polyethylene terephthalate, polybutylene terephthalate, polyamide, thermoplastic polyurethane, polycarbonate, and polypropylene.

9. The flame-retardant coloring composition of polymeric materials according to claim 8, characterized in that, The polymeric material flame-retardant coloring composition further comprises one or more phosphorus- or nitrogen-containing flame retardants, wherein the phosphorus- or nitrogen-containing flame retardants are selected from one or more combinations of aluminum hypophosphite, intumescent flame retardants, and phosphate flame retardants.

10. A method for solution coloring and flame-retardant modification of a polymer material, characterized in that, The DPP-type phosphorus-containing colored flame retardant according to any one of claims 1-5 is melt-blended with a polymer resin and molded to obtain a flame-retardant colored product, wherein the melt-blending temperature is 200-300℃.

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