Preparation method and application of flame-retardant polyester polyol containing DOPO, and preparation method of flame-retardant polyurethane

Abstract

The present invention relates to the field of flame retardant technology, and in particular to a method for preparing and applying a flame-retardant polyester polyol containing DOPO, and a method for preparing flame-retardant polyurethane. The preparation method of the present invention overcomes the drawbacks of the prior art, such as complex processes, low DOPO content, and environmental pollution. Furthermore, the method utilizes simple raw materials, produces no byproducts other than water, requires no post-processing, and has low equipment requirements during the synthesis process. The flame-retardant polyester polyol containing DOPO prepared using the above-mentioned preparation method is a linear molecule. When used in the synthesis of flame-retardant polyurethane, even if the content of the flame-retardant polyester polyol is as high as 50%, it will not cause crosslinking of the system. Furthermore, due to the high DOPO content, the flame-retardant properties are very ideal, significantly improving the flame-retardant properties of flame-retardant polyesters and polyester polyols.

Description

Technical Field

[0001] The present invention relates to the field of flame retardant technology, and in particular to a preparation method and application of a flame retardant polyester polyol containing DOPO, and a preparation method of flame retardant polyurethane. Background Art

[0002] Flame-retardant polymer materials are attracting increasing attention due to their significant safety benefits in fire and disaster prevention. Polymers containing aromatic organophosphorus flame retardants are becoming a key development direction in the synthesis of flame-retardant polyesters and polyurethanes due to their outstanding efficiency, safety, and non-toxicity. Chemically grafted flame-retardant polymers overcome shortcomings such as poor matrix compatibility, susceptibility to leaching, and poor water resistance, and are expected to find application in a wider range of fields. 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives possess heterocyclic phosphorus-containing properties, and the phosphaphenanthrene groups are easily incorporated into the polymer molecular structure, exhibiting excellent flame retardancy, thermal stability, and chemical stability, making them ideal flame-retardant organic molecules for chemical modification. Existing technologies primarily prepare DOPO derivatives by grafting reactive groups onto the DOPO structure, or by synthesizing chemically grafted flame-retardant polymers through addition reactions of DOPO with C=C double bonds and C≡C triple bonds. For example, application number CN20131008612.0 discloses a curable reactive flame retardant monomer molecule with an active double bond and a DOPO flame retardant group, which can be used to flame retard a variety of polymer resins containing unsaturated double bonds, such as epoxy acrylic resin and unsaturated polyester resin. However, the synthesis process is relatively complex and requires the use of reagents such as organic solvents and acid binders. The synthesis conditions require an inert atmosphere and low temperature. Chinese patent application number CN201510443198.5 discloses a DOPO-type reactive flame retardant with an epoxy end group and a preparation method thereof. DOPO and a polyglycidyl compound are used as raw materials to prepare a reactive flame retardant containing a DOPO flame retardant group and an epoxy end group. The reactive flame retardant can be used as a capped flame retardant for the flame retardancy of polyurethane materials. Because it can only be used as a capping agent in the synthesis of flame-retardant polyurethane, the amount added is limited. Patents CN201510032241.9 and CN201910367036.6 disclose methods for synthesizing DOPO-modified polyesters: DOPO is dissolved in a suitable solvent and then reacted with an unsaturated dibasic acid under heating to prepare a DOPO-containing dibasic acid. This dibasic acid is then esterified with a polyol to synthesize a DOPO-chemically grafted polyester. The unsaturated dibasic acid used in this synthesis route undergoes a free radical addition reaction with the pH of DOPO at high temperatures, while also undergoing self-polymerization between C=C double bonds. This facilitates cross-linking of the polymer molecules. Furthermore, the significant steric hindrance of the dibasic acid after grafting DOPO complicates the esterification reaction, resulting in a low molecular weight and low organophosphorus content in the resulting polyester polyol.

[0003] It can be seen that the flame-retardant polyester polyols in the prior art have the defect of low DOPO content, which limits the improvement of flame retardancy. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a flame-retardant polyester polyol containing DOPO, and a preparation method of a flame-retardant polyurethane. The preparation method can obtain a flame-retardant polyester polyol with a high DOPO content and good flame retardant performance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a flame-retardant polyester polyol containing DOPO, comprising the following steps:

[0007] Mixing polyol, dibasic acid and polymerization inhibitor, and performing a precondensation reaction to obtain an unsaturated polyester prepolymer;

[0008] The unsaturated polyester prepolymer is mixed with DOPO and its derivatives, and then subjected to addition reaction and condensation reaction in sequence to obtain the flame-retardant polyester polyol containing DOPO;

[0009] The molar ratio of the DOPO and its derivatives to the C=C double bonds in the unsaturated polyester prepolymer is 1:1;

[0010] The mass percentage of DOPO and its derivatives in the DOPO-containing flame-retardant polyester polyol is 30-60%;

[0011] The flame retardant polyester polyol containing DOPO is a linear molecule.

[0012] Preferably, the molar ratio of the polyol to the dibasic acid is (1-19): (1-10);

[0013] The dibasic acid includes a saturated dibasic acid and an unsaturated dibasic acid, and the molar ratio of the saturated dibasic acid to the unsaturated dibasic acid is (0-9):(1-10).

[0014] Preferably, the polyol includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane;

[0015] The saturated dibasic acid includes one or more of succinic acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid and phthalic acid;

[0016] The unsaturated dibasic acid includes one or more of itaconic acid, maleic acid, fumaric acid and unsaturated fatty acid.

[0017] Preferably, the mass of the polymerization inhibitor is 0.1 to 2.0% of the total mass of the polyol and the dibasic acid;

[0018] The polymerization inhibitor includes one or more of hydroquinone, tetrachlorobenzoquinone, 1,4-naphthoquinone, tert-butylcatechol, 4-methoxyphenol, methylhydroquinone, 4,6-dinitro-o-sec-butylphenol and 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one.

[0019] Preferably, the process of the pre-condensation reaction is: heating from room temperature to 130-135° C. and keeping the temperature for 1.0-3.0 hours, then heating to 145-150° C. and keeping the temperature for 1.0-3.0 hours, then heating to 160-165° C. and keeping the temperature for 1.0-3.0 hours, and finally heating to 170-175° C. and keeping the temperature for 1.0-3.0 hours.

[0020] Preferably, the mixing temperature of the unsaturated polyester prepolymer and DOPO and its derivatives is 140-155°C;

[0021] The temperature of the addition reaction is 120-165° C., and the time is 4.0-8.0 hours.

[0022] Preferably, the condensation reaction process is: heating from 150-160°C to 175-180°C and keeping it for 1.0-3.0h, then heating to 190-210°C and keeping it for 1.0-3.0h, and then heating to 210-235°C and keeping it for 1.0-3.0h;

[0023] The criterion for the completion of the condensation reaction is an acid value ≤ 5 mg KOH / g.

[0024] The present invention also provides the use of the flame-retardant polyester polyol containing DOPO prepared by the preparation method described in the above technical solution in the preparation of flame-retardant polyurethane.

[0025] The present invention also provides a method for preparing flame-retardant polyurethane, comprising the following steps:

[0026] The flame-retardant polyester polyol containing DOPO prepared by the preparation method described in the above technical solution, polyol, diisocyanate, catalyst and solvent are mixed and reacted to obtain the flame-retardant polyurethane.

[0027] Preferably, the polyol includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane;

[0028] The diisocyanate includes one or more of 4,4-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate;

[0029] The catalyst includes an organometallic catalyst;

[0030] The solvent includes one or more of acetone, N,N-dimethylformamide and ethyl acetate.

[0031] The present invention provides a method for preparing a flame-retardant polyester polyol containing DOPO, comprising the following steps: mixing a polyol, a dibasic acid, and a polymerization inhibitor, and performing a precondensation reaction to obtain an unsaturated polyester prepolymer; mixing the unsaturated polyester prepolymer with DOPO and its derivatives, and sequentially performing an addition reaction and a condensation reaction to obtain the flame-retardant polyester polyol containing DOPO; the molar ratio of the C=C double bonds in the DOPO and its derivatives to the unsaturated polyester prepolymer is 1:1; the mass percentage of DOPO and its derivatives in the flame-retardant polyester polyol containing DOPO is 30-60%; and the flame-retardant polyester polyol containing DOPO is a linear molecule. The preparation method of the present invention overcomes the shortcomings of the prior art, such as complex processes, low DOPO content, and environmental pollution. Furthermore, the method uses simple raw materials, produces no byproducts other than water, requires no post-processing of the product, and has low equipment requirements during the synthesis process. The flame-retardant polyester polyol containing DOPO prepared using the above preparation method is a linear molecule. When used in the synthesis of flame-retardant polyurethane, the mass percentage of the DOPO-containing flame-retardant polyester polyol in the flame-retardant polyurethane can be as high as 50% without causing crosslinking of the system. Furthermore, due to the high DOPO content, the flame-retardant properties are very good, significantly improving the flame-retardant properties of flame-retardant polyesters and polyester polyols. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 (a) is an infrared spectrum of the unsaturated polyester prepolymer described in Example 1; (b) is an infrared spectrum of the unsaturated polyester prepolymer and the DOPO-grafted polyester polyol;

[0033] Figure 2 This is a diagram showing the effect of using the polyurethane described in Application Example 1 for flame retardant fabrics;

[0034] Figure 3 This is a schematic diagram of the preparation process of the flame-retardant polyester polyol containing DOPO according to the present invention. DETAILED DESCRIPTION

[0035] The present invention provides a method for preparing a flame-retardant polyester polyol containing DOPO, comprising the following steps:

[0036] Mixing polyol, dibasic acid and polymerization inhibitor, and performing a precondensation reaction to obtain an unsaturated polyester prepolymer;

[0037] The unsaturated polyester prepolymer is mixed with DOPO and its derivatives, and addition reaction and condensation reaction are carried out in sequence to obtain the flame retardant polyester polyol containing DOPO (such as Figure 3 Steps ① and ② shown in the figure);

[0038] The molar ratio of the DOPO and its derivatives to the C=C double bonds in the unsaturated polyester prepolymer is 1:1;

[0039] The mass percentage of DOPO and its derivatives in the DOPO-containing flame-retardant polyester polyol is 30-60%;

[0040] The flame retardant polyester polyol containing DOPO is a linear molecule.

[0041] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0042] The present invention mixes polyol, dibasic acid and polymerization inhibitor, and performs precondensation reaction to obtain unsaturated polyester prepolymer.

[0043] In the present invention, the polyol preferably includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane. When the polyol is two or more of the above-mentioned specific selections, the present invention has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0044] In the present invention, the dibasic acid preferably includes a saturated dibasic acid and an unsaturated dibasic acid; the molar ratio of the saturated dibasic acid to the unsaturated dibasic acid is preferably (0-9):(1-10), more preferably (1-8):(2-8), and most preferably (4-6):(3-5). In the present invention, the saturated dibasic acid preferably includes one or more of succinic acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, and phthalic acid. When the saturated dibasic acid is two or more of the above-mentioned specific selections, the present invention has no special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0045] In the present invention, the unsaturated dibasic acid preferably includes one or more of itaconic acid, maleic acid, fumaric acid and unsaturated fatty acids. When the unsaturated dibasic acid is two or more of the above-mentioned specific selections, the present invention has no special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0046] In the present invention, the molar ratio of the polyol to the dibasic acid is preferably (1-19):(1-10), more preferably (3-16):(2-8), and most preferably (7-11):(3-5).

[0047] In the present invention, the polymerization inhibitor preferably includes one or more of hydroquinone, tetrachlorobenzoquinone, 1,4-naphthoquinone, tert-butylcatechol, 4-methoxyphenol, methylhydroquinone, 4,6-dinitro-o-sec-butylphenol and 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one. When the polymerization inhibitor is two or more of the above-mentioned specific selections, the present invention has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0048] In the present invention, the mass of the polymerization inhibitor is preferably 0.1 to 2.0% of the total mass of the polyol and the dibasic acid, more preferably 0.3 to 1.6%, and most preferably 0.6 to 1.2%.

[0049] The present invention effectively solves the problem of reaction difficulties caused by steric hindrance by first prepolymerizing (precondensation reaction) and then grafting (subsequent addition reaction) under the protection of a polymerization inhibitor. This is mainly because the present invention uses the polymerization inhibitor to protect unsaturated C=C double bonds during the prepolymerization reaction (precondensation reaction) and grafting reaction (subsequent addition reaction), effectively preventing the formation of chemical crosslinking points in the reaction system, thereby obtaining linear polymer molecules. The finally prepared flame-retardant polyester polyol containing DOPO has this linear structure and bifunctionality (the flame-retardant polyester polyol has a linear structure with an active hydroxyl group at each end, and the molecule is bifunctional). Therefore, no chemical crosslinking points are introduced when used in a polyurethane synthesis reaction. Therefore, even when the content is as high as 40-60%, the system will not be crosslinked.

[0050] In the present invention, the mixing is preferably performed by first mixing the polyol, dibasic acid, and unsaturated dibasic acid, then adding a polymerization inhibitor and stirring. In the present invention, the stirring speed is preferably 100-500 r / min, more preferably 200-350 r / min, and the stirring time is preferably 0.5-2.5 hours, more preferably 1.0-2.0 hours. In the present invention, the stirring process is accompanied by a temperature increase, and the target temperature of the temperature increase is preferably 130°C.

[0051] In the present invention, the process of the pre-condensation reaction is preferably programmed temperature rise in 3 to 4 gradients within the range of 130 to 175°C; more preferably, the temperature is raised from room temperature to 130 to 135°C and kept for 1.0 to 3.0 hours, then raised to 145 to 150°C and kept for 1.0 to 3.0 hours, then raised to 160 to 165°C and kept for 1.0 to 3.0 hours, then raised to 170 to 175°C and kept for 1.0 to 3.0 hours; further preferably, the temperature is raised from room temperature to 130 to 134°C and kept for 1.5 to 2 hours. The temperature is preferably increased from room temperature to 130-133°C and kept warm for 1.5-2.2 hours, then increased to 145-148°C and kept warm for 1.5-2.2 hours, then increased to 160-163°C and kept warm for 1.5-2.2 hours, and then increased to 172-175°C and kept warm for 1.5-2.2 hours.

[0052] In the present invention, during the pre-condensation reaction, water is preferably removed by adding a water-carrying agent, passing nitrogen, or vacuuming. In the present invention, the water-carrying agent is preferably one or more of benzene, toluene, and xylene. When the water-carrying agent is two or more of the above-mentioned specific options, the present invention does not have any particular restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. The present invention does not have any particular restrictions on the nitrogen-passing process, and a process familiar to those skilled in the art can be used.

[0053] After obtaining the unsaturated polyester prepolymer, the present invention mixes the unsaturated polyester prepolymer with DOPO and its derivatives, and sequentially performs addition reaction and condensation reaction to obtain the flame-retardant polyester polyol containing DOPO.

[0054] The present invention does not have any special limitation on the type of the DOPO derivative, and any type of DOPO derivative well known to those skilled in the art can be used.

[0055] In the present invention, the mixing temperature is preferably 140-155°C, more preferably 143-150°C, and most preferably 145-150°C; the mixing is preferably carried out under stirring conditions. The present invention does not have any special limitation on the stirring process, and the process well known to those skilled in the art can be used.

[0056] In the present invention, the mixing is preferably performed by adding the DOPO and its derivatives into the unsaturated polyester prepolymer.

[0057] In the present invention, the temperature of the addition reaction is preferably 120-165° C., more preferably 130-160° C., most preferably 145-160° C.; the time is preferably 4.0-8.0 h, more preferably 5.0-7.0 h, most preferably 5.5-6.5 h.

[0058] In the present invention, the addition reaction has high reactivity within the above temperature range, which is beneficial to improving the grafting density and increasing the grafting rate, and can make the grafting rate of the DOPO and its derivatives ≥95%, and can increase the content of flame retardant components in the synthesized polyester.

[0059] In the present invention, the condensation reaction is preferably subjected to programmed temperature increase in 2 to 4 gradients within the range of 175 to 230°C; more preferably, the temperature is increased from 120 to 165°C to 175 to 180°C and kept for 1.0 to 3.0 hours, then increased to 190 to 210°C and kept for 1.0 to 3.0 hours, and then increased to 210 to 235°C and kept for 1.0 to 3.0 hours; most preferably, the temperature is increased from 145 to 160°C to 170 to 180°C and kept for 1.5 to 2.5 hours, then increased to 195 to 205°C and kept for 1.5 to 2.5 hours, and finally increased to 215 to 230°C and kept for 1.5 to 2.5 hours.

[0060] After the condensation reaction is completed, the present invention also preferably includes a water removal process, and the water removal method is preferably vacuuming. In the present invention, the vacuuming temperature is preferably 200-230°C, and the vacuum degree is preferably 0.02-0.08MPa.

[0061] In the present invention, the standard for completion of the condensation reaction is preferably an acid value ≤ 5 mg KOH / g.

[0062] The present invention also provides the use of the flame-retardant polyester polyol containing DOPO prepared by the preparation method described in the above technical solution in the preparation of flame-retardant polyurethane.

[0063] The present invention also provides a method for preparing flame-retardant polyurethane, comprising the following steps:

[0064] The flame-retardant polyester polyol containing DOPO prepared by the preparation method described in the above technical solution, polyol, diisocyanate, catalyst and solvent are mixed and reacted to obtain the flame-retardant polyurethane.

[0065] In the present invention, the polyol preferably includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane. When the diol is two or more of the above-mentioned specific selections, the present invention has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0066] In the present invention, the diisocyanate preferably includes one or more of 4,4-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate. When the diisocyanate is two or more of the above-mentioned specific selections, the present invention has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0067] In the present invention, the catalyst preferably includes an organic metal catalyst, more preferably an organic tin catalyst and / or an organic bismuth catalyst; the organic tin catalyst preferably includes dibutyltin dilaurate (T-12) and / or stannous octoate; the organic bismuth catalyst preferably includes BACT-E20CX and / or BCAT-T100R; when the catalyst is two or more of the above-mentioned specific options, the present invention has no special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0068] In the present invention, the solvent preferably includes one or more of acetone, N,N-dimethylformamide, and ethyl acetate. When the solvent includes two or more of the above-mentioned specific selections, the present invention does not have any particular restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. The hydrophilic diol is preferably one or more of PEG-400, PEG-800, PEG-1000, dimethylolpropionic acid, dimethylolbutanoic acid, and sodium 1,2-dihydroxy-3-propanesulfonate. When the solvent includes two or more of the above-mentioned specific selections, the present invention does not have any particular restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0069] In the present invention, the molar ratio of the polyol, the flame retardant polyester polyol containing DOPO and the diisocyanate is preferably 1:(0-1):(0.5-2), more preferably 1:(0.1-0.9):(0.8-1.6), and most preferably 1:(0.1-0.8):(1.0-1.4).

[0070] In the present invention, the mass percentage of the catalyst to the total mass of the flame retardant polyester polyol, polyol and diisocyanate is preferably 0.1-1.0%, more preferably 0.2-0.9%, most preferably 0.3-0.6%.

[0071] In the present invention, the mass percentage of the solvent to the total mass of the flame-retardant polyester polyol, polyol, and diisocyanate is preferably 2-20%, more preferably 4-16%, and most preferably 8-12%. In the present invention, the solvent is used to adjust the viscosity of the reaction system. Therefore, the solvent is used to maintain the viscosity of the reaction system during the subsequent reaction process.

[0072] In the present invention, the mixture preferably also includes a hydrophilic diol, and the hydrophilic diol preferably includes PEG-400, PEG-800, PEG-1000, dimethylol propionic acid, dimethylol butyric acid and / or sodium 1,2-dihydroxy-3-propanesulfonate. When the hydrophilic diol is two of the above-mentioned specific options, the present invention does not have any special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0073] In the present invention, the mass of the hydrophilic diol preferably accounts for 0.1 to 1.0% of the total mass of the polyol and the polyacid, more preferably 0.2 to 0.9%, and most preferably 0.2 to 0.6%.

[0074] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0075] In the present invention, the reaction temperature is preferably 60-90°C, more preferably 65-85°C, and most preferably 70-80°C; the reaction time is preferably 3.0-6.0 hours, more preferably 3.5-5.5 hours, and most preferably 4.0-5.0 hours. In the present invention, the reaction is preferably carried out under stirring conditions. The present invention does not have any particular limitation on the stirring process, and the process well known to those skilled in the art can be used.

[0076] After the reaction is completed, the present invention further preferably includes cooling. The present invention does not have any special limitation on the cooling process, and the cooling process can be carried out using a process well known to those skilled in the art.

[0077] The preparation method and application of the flame-retardant polyester polyol containing DOPO and the preparation method of the flame-retardant polyurethane provided by the present invention are described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0078] Example 1

[0079] 4.0 mol of 1,6-hexanediol, 1.5 mol of adipic acid, and 2.0 mol of itaconic acid were mixed in a reactor at a molar ratio of 8:3:4, 0.5% of hydroquinone relative to the total mass of the 1,6-hexanediol, adipic acid, and itaconic acid was added, and the mixture was heated and mechanically stirred until completely dissolved; nitrogen was introduced into the reactor, and the temperature was increased gradually to carry out a precondensation reaction, wherein the gradient temperature increase program was 130° C. for 1.5 h, 145° C. for 1.5 h, 160° C. for 1.5 h, and 175° C. for 1.5 h, to obtain an unsaturated polyester prepolymer;

[0080] The temperature of the reactor was lowered to 150° C., and then an equimolar amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (phosphaphenanthrene flame retardant, DOPO) to itaconic acid was added under stirring. The temperature was then raised to 155° C. and kept for 4 hours. A gradient temperature increase was performed, wherein the gradient temperature increase program was 175° C. for 2.0 hours, 200° C. for 2.0 hours, and 220° C. for 2.0 hours. During the entire reaction process, vacuum (vacuum degree of 0.08 MPa) was used to remove the byproduct H2O. The reaction was stopped when the acid value was lower than 5 mg KOH / g to obtain a DOPO-grafted polyester polyol.

[0081] The parameter information of the DOPO-grafted polyester polyol is shown in Table 1:

[0082] Table 1 Parameters of the DOPO-grafted polyester polyols

[0083] serial number project parameter Detection method 1 Appearance Light yellow viscous liquid visual 2 Number average molecular weight 2400-2600 GPC 3 Hydroxyl value 42±5mgKOH / g HG / T2709-1995 4 Acid value 5mgKOH / g HG / T2708-1995 5 DOPO content 34％ Theoretical calculations 6 Grafting rate ＞95％ Titration

[0084] The unsaturated polyester prepolymer and the DOPO grafted polyester polyol were subjected to infrared spectroscopy test, and the test results were as follows: Figure 1 As shown, a is the infrared spectrum of the unsaturated prepolymer, b is the infrared spectrum of the DOPO grafted polyester polyol; Figure 1 It can be seen that the unsaturated polyester prepolymer has a -1 The characteristic peak of the unsaturated C=C double bond at 1500-1650 cm-1 disappears after addition of DOPO. -1 The characteristic absorption peak of the benzene ring in DOPO appears.

[0085] Example 2

[0086] 4.0 mol of 1,6-hexanediol, 2.0 mol of neopentyl glycol, and 4.0 mol of maleic acid are mixed in a reactor at a molar ratio of 2:1:2, and 0.8% of 4-methoxyphenol relative to the total mass of the 1,6-hexanediol, neopentyl glycol, and maleic acid is added and mechanically stirred until completely dissolved; a water separator is installed on the reactor, and toluene is added to the reactor in an amount of 10% of the total mass of the dibasic acid and diol to remove the by-product H2O, and a pre-condensation reaction is carried out by gradient heating, wherein the gradient heating program is 135°C for 1.5 h, 150°C for 1.5 h, 165°C for 1.0 h, and 175°C for 1.0 h to obtain an unsaturated polyester prepolymer;

[0087] The temperature of the reactor was lowered to 140° C., and then an equimolar amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (phosphaphenanthrene flame retardant, DOPO) to maleic acid was added under stirring. The temperature was then raised to 150° C. and kept for 6 hours, followed by a gradient temperature increase. The gradient temperature increase program was 175° C. for 2.0 hours, 205° C. for 2.0 hours, and 220° C. for 2.0 hours. During the entire reaction process, vacuum (vacuum degree of 0.06 MPa) was used to remove the byproduct H2O. The reaction was stopped when the acid value was lower than 5 mg KOH / g to obtain a DOPO-grafted polyester polyol.

[0088] The parameter information of the DOPO-grafted polyester polyol is shown in Table 2:

[0089] Table 2 Parameters of the DOPO-grafted polyester polyols

[0090] serial number project parameter Detection method 1 Appearance Light yellow viscous liquid visual 2 Molecular weight 850～1050 GPC 3 Hydroxyl value 120±5mgKOH / g HG / T2709-1995 4 Acid value 5mgKOH / g HG / T2708-1995 5 DOPO content 46％ Theoretical calculations 6 Grafting rate ＞95％ Titration

[0091] Application Example 1

[0092] According to the molar ratio of 1.1:1.0:0.03, 0.55 mol of hexamethylene diisocyanate, 0.5 mol of polyester diol (molecular weight of 1000) and 0.015 mol of the DOPO-grafted polyester polyol described in Example 1 were placed in a reactor, 5% of ethyl acetate relative to the total mass of the hexamethylene diisocyanate, polyester diol and DOPO-grafted polyester polyol and 0.5% of T-12 relative to the total mass of the hexamethylene diisocyanate, polyester diol and DOPO-grafted polyester polyol were added, and the reaction was carried out at 75°C for 6 hours. During the reaction, the viscosity of the reaction system was adjusted with an appropriate amount of ethyl acetate. After the reaction was completed, the reaction was naturally cooled and the material was coated on the surface of nylon fabric for verification of flame retardancy. The test results are as follows: Figure 2 As shown by Figure 2It can be seen that the DOPO-grafted polyurethane has a significant flame retardant effect when used for the modification of nylon fabrics, and achieves the effect of self-extinguishing when away from fire.

[0093] Application Example 2

[0094] 0.55 mol of isophorone diisocyanate, 0.25 mol of polypropylene glycol (molecular weight 1000), and 0.25 mol of the DOPO-grafted polyester polyol described in Example 2 were placed in a reactor in a molar ratio of 1.1:0.5:0.5. 10% of acetone relative to the total mass of the isophorone diisocyanate, polypropylene glycol, and DOPO-grafted polyester polyol and 0.3% of T-12 relative to the total mass of the isophorone diisocyanate, polypropylene glycol, and DOPO-grafted polyester polyol were added. The mixture was reacted at 75° C. for 5 h. During the reaction, an appropriate amount of acetone was used to adjust the viscosity of the reaction system. After the reaction was completed, the mixture was naturally cooled and discharged to obtain a flame-retardant polyurethane.

[0095] The flame retardant polyurethane was tested for flame retardancy according to the vertical method in GB / T24081996. The test result showed that the flame retardant grade of the flame retardant polyurethane was V0.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a flame-retardant polyester polyol containing DOPO, characterized in that: It consists of the following steps: A polyol, a dibasic acid and a polymerization inhibitor are mixed and subjected to a precondensation reaction to obtain an unsaturated polyester prepolymer; the dibasic acid is a saturated dibasic acid and an unsaturated dibasic acid, and the molar ratio of the saturated dibasic acid to the unsaturated dibasic acid is (0-9): (1-10); the polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane; the saturated dibasic acid is one or more of succinic acid, adipic acid, suberic acid and sebacic acid; the unsaturated dibasic acid is one or more of itaconic acid, maleic acid and fumaric acid; The unsaturated polyester prepolymer and DOPO are mixed, and addition reaction and condensation reaction are carried out in sequence to obtain the flame-retardant polyester polyol containing DOPO; the temperature of the addition reaction is 120-165° C., and the time is 4.0-8.0 hours; The molar ratio of the DOPO to the C=C double bonds in the unsaturated polyester prepolymer is 1:1; The mass percentage of DOPO in the DOPO-containing flame-retardant polyester polyol is 30-60%; The flame retardant polyester polyol containing DOPO is a linear molecule, each end of the flame retardant polyester polyol containing DOPO has an active hydroxyl group, the molecule is bifunctional; The pre-condensation reaction process is: from room temperature to 130~135 ℃ heat 1.0~3.0h, raised to 145~150 ℃ heat 1.0~3.0h, raised to 160~165 ℃ heat 1.0~3.0h, raised to 170~175 ℃ heat 1.0~3.0h; The mass of the polymerization inhibitor is 0.1-2.0% of the total mass of the polyol and the dibasic acid; The polymerization inhibitor includes one or more of hydroquinone, tetrachlorobenzoquinone, 1,4-naphthoquinone, tert-butylcatechol, 4-methoxyphenol, methylhydroquinone, 4,6-dinitro-o-sec-butylphenol and 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadiene-1-one.

2. The preparation method according to claim 1, wherein The molar ratio of the polyol to the dibasic acid is (1-19): (1-10).

3. The preparation method according to claim 1, wherein The mixing temperature of the unsaturated polyester prepolymer and DOPO is 140-155°C.

4. The preparation method according to claim 1, wherein The condensation reaction process is as follows: heating from 150-160° C. to 175-180° C. and keeping the temperature for 1.0-3.0 h, then heating to 190-210° C. and keeping the temperature for 1.0-3.0 h, and finally heating to 210-235° C. and keeping the temperature for 1.0-3.0 h; The criterion for the completion of the condensation reaction is an acid value ≤ 5 mg KOH / g.

5. Use of the flame-retardant polyester polyol containing DOPO prepared by the preparation method according to any one of claims 1 to 4 in the preparation of flame-retardant polyurethane.

6. A method for preparing flame-retardant polyurethane, characterized in that: The following steps are involved: The flame-retardant polyester polyol containing DOPO prepared by the preparation method according to any one of claims 1 to 4, polyol, diisocyanate, catalyst and solvent are mixed and reacted to obtain the flame-retardant polyurethane.

7. The preparation method according to claim 6, wherein The polyol includes one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, diethylene glycol, dipropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2-ethylhexanediol, 3-methyl-1,5-pentanediol, polyethylene glycol, polypropylene glycol, glycerol and trimethylolpropane; The diisocyanate includes one or more of 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, toluene diisocyanate, p-phenylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate; The catalyst includes an organometallic catalyst; The solvent includes one or more of acetone, N,N-dimethylformamide and ethyl acetate.

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