A method for preparing flame retardant polycarbonate polyol

Abstract

The invention discloses a method for preparing a flame retardant polycarbonate polyol, wherein pyridine diol or bipyridine diol, small molecule carbonate and other polyols are used as raw materials, and polycondensation reaction is carried out in the presence of a catalyst to generate polycarbonate polyol. The advantage of the product is that it has good autocatalytic performance during the synthesis process, and because of the presence of the pyridine structure, the product has good flame retardant properties and mechanical properties such as tensile strength.

Description

Technical Field

[0001] The invention relates to the field of polyols, and in particular to a method for preparing flame retardant polycarbonate polyol. Background Art

[0002] Polycarbonate polyol is a polyol product with hydroxyl groups at the ends of the molecular chain and carbonate-based repeating units in the main molecular chain. The polyurethane elastomer prepared from polycarbonate polyol has similar mechanical properties to other conventional polyester-type polyurethane elastomers, and has better hydrolysis stability.

[0003] The mainstream polycarbonate polyol manufacturers on the market now all use the process of ester exchange between carbonate and small molecule diol to synthesize the product. In the invention patent CN201711286414.5, under the protection of inert gas, the polycarbonate polyol product is obtained by ester exchange between small molecule polyol and carbonate. However, polycarbonate polyol needs to have certain flame retardant properties in some application performances, but currently polycarbonate polyols are mostly made of carbonate and long carbon chain diols, and the flame retardant properties are poor. In the application scenarios that require flame retardant properties, flame retardants need to be added to make the products have flame retardant properties. However, the added flame retardant will affect other performance indicators of polycarbonate polyol, and the added flame retardant is easy to migrate during the use of the product, resulting in a short-lasting flame retardant effect and affecting the performance.

[0004] In some fields, the tensile strength of polyurethane elastomers is extremely high. Although the tensile strength of polycarbonate polyurethane elastomers can meet conventional requirements, it still cannot meet the requirements of some fields with higher tensile strength requirements. In addition, there is a common problem in the synthesis process of polycarbonate polyols, that is, the reaction cycle is very long, generally reaching more than 45 hours, so how to improve the reactivity of polycarbonate polyols is also a key focus of researchers.

[0005] Therefore, the performance of polycarbonate polyurethane elastomers is closely related to the structure of polycarbonate polyols. How to improve the mechanical properties of polyurethane elastomers, especially tensile strength, and improve reaction activity and practical value by designing a new polycarbonate polyol and its preparation method is of great positive significance. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a method for preparing a flame-retardant polycarbonate polyol. By using pyridine diol or bipyridine diol as a raw material for preparing polycarbonate polyol, the product has a certain self-catalytic effect due to the addition of special polyols, and can effectively reduce the reaction cycle of polycarbonate polyols. In addition, the prepared polyol has a flame-retardant polycarbonate polyol product due to its special structure. In the process of preparing downstream products, no external flame retardant is required. The product itself has a flame retardant effect, avoiding the influence of the application performance caused by the external flame retardant, and at the same time, the tensile performance of the product is further improved.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a flame-retardant polycarbonate polyol, which uses pyridine diol or bipyridine diol, small molecular carbonate, and other polyols as raw materials, and performs polycondensation reaction in the presence of a catalyst to generate polycarbonate polyol;

[0009] Preferably, in the reaction system, taking the total mass of the following raw materials as 100%, the mass proportions of the various substances are:

[0010] Pyridine diol or bipyridine diol 20-50%, preferably 25-45%

[0011] Small molecule carbonate 30-70%, preferably 35-55%

[0012] Other diols 10-30%, preferably 15-25%

[0013] In the present invention, the amount of the catalyst used is 100-200 ppm, preferably 120-150 ppm, based on the total mass of the raw materials.

[0014] In the present invention, the catalyst is one or more of tetrabutyl titanate, tetraisopropyl titanate, dibutyltin dilaurate, stannous octoate, dibutyltin octoate, trimethylamine, triethylamine, tripropylamine, and p-toluenesulfonic acid, among which tetrabutyl titanate is preferred.

[0015] In the present invention, the pyridine diol or bipyridine diol is one or more of 2,3-pyridine diol, 2,4-pyridine diol, 2,5-pyridine diol, 2,2'-bipyridine-3,3'-diol, 2,2'-bipyridine-5,5'-diol, 2,2'-bipyridine-4,4'-diol, among which 2,2'-bipyridine-3,3'-diol is preferred.

[0016] In the present invention, the other diols are selected from one or more of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propylene glycol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol, preferably one or more of diethylene glycol and triethylene glycol.

[0017] In the present invention, the method for preparing the flame retardant polycarbonate polyol is characterized in that the small molecule carbonate is one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate and diphenyl carbonate.

[0018] In the present invention, the preparation method of the polyester polyol adopts a batch process, and the reactor adopts a kettle reactor.

[0019] In the present invention,

[0020] Specifically, the preparation method is as follows: adding various raw materials in a nitrogen atmosphere, heating to 160-250° C., preferably 180-210° C., at normal pressure, keeping the temperature and reacting at normal pressure for a period of time, and then evacuating the mixture to continue the reaction until the hydroxyl value of the product reaches the designed hydroxyl value ±10 mg KOH / g and then stopping the reaction.

[0021] In the present invention, the reaction time at normal pressure is 5-10 hours, preferably 6-8 hours.

[0022] In the present invention, the reaction time under vacuum conditions is 5-10 h, preferably 10-15 h, and the vacuum conditions are an absolute pressure of 1-10 kPa, preferably 1-5 kPa.

[0023] The flame retardant polycarbonate polyol prepared by the preparation method of the present invention can be used to prepare polyurethane elastomers. The prepared polyurethane elastomers have good mechanical properties, especially high tensile strength.

[0024] Preferably, the polyurethane elastomer adopts a traditional elastomer synthesis process, and the polyurethane elastomer includes the following raw material components in parts by weight: 25-35 parts of isocyanate, 5-9 parts of chain extender, 50-60 parts of the polycarbonate polyol described in the present invention, 2-5 parts of antioxidant and 0.4-2 parts of catalyst.

[0025] In the polyurethane elastomer of the present invention, the isocyanate may be one of MDI, TDI or IDPI; the chain extender is ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol or 1,5-pentanediol; the antioxidant is mainly a long-chain ester, which may be antioxidant 245, 1010, 1035, 1076 or 1098; the catalyst is a tertiary amine, which may be triethylenediamine, cyclohexylmethyl tertiary amine, pentamethyldialkylenetriamine or tetramethylalkylenediamine.

[0026] The polycarbonate polyol prepared by the method of the present invention has the following beneficial effects:

[0027] ① Since the ammonia nitrogen group can catalyze this reaction, the presence of the raw material pyridine diol makes the synthesis process of polycarbonate polyol have a self-catalytic effect, which can effectively reduce the reaction time and improve the production efficiency;

[0028] ② The polycarbonate polyol product synthesized by this process can effectively improve the flame retardant properties of the product while ensuring the basic performance due to the presence of the rigid pyridine ring and its nitrogen element, thus meeting the use requirements of applications with flame retardant requirements. DETAILED DESCRIPTION

[0029] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0030] The reactants involved in the present invention are all purchased from commercially available pure products unless otherwise specified.

[0031] Preparation of polyurethane elastomer: 6 parts by mass of 1,4-butanediol, 55 parts by mass of the polycarbonate diol prepared in various embodiments of the present invention, 3 parts by mass of antioxidant 1076 and 1 part by mass of tetramethylalkylene diamine were mixed, and then 35 parts by mass of TDI were added, the temperature was raised to 75°C, and the molding was performed by compression molding. After aging for 20 hours, the performance test was performed.

[0032] The test method involved in the present invention is:

[0033] Hydroxyl value: The hydroxyl value of polyester polyol products refers to GBT 12008.5-2009;

[0034] Oxygen index: The oxygen index of polyester polyols refers to GBT 10802-2006.

[0035] [Example 1]

[0036] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 3.5kg of 2,3-pyridinediol, 5kg of dimethyl carbonate, and 1.5kg of diethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 130ppm of tetrabutyl titanate accounting for the total mass of the above raw materials was added as a catalyst. Start the reaction, heat to 210°C under normal pressure, keep warm for 8h, evacuate to 5kPa, continue the reaction for 12h, cool down, and discharge to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value is 61mg KOH / g. According to the specific embodiment of the present invention, it is prepared into a polyurethane elastomer, the product oxygen index is 28.5%, and the elastomer tensile strength is 46.7MPa.

[0037] [Example 2]

[0038] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 3kg of 2,4-pyridinediol, 4.5kg of dimethyl carbonate, and 2kg of diethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 120ppm of tetraisopropyl titanate accounting for the total mass of the above raw materials was added as a catalyst. The reaction was started, and the temperature was raised to 200°C under normal pressure and then kept warm for 6h, and then evacuated to 3kPa, and the reaction was continued for 15h, and the temperature was lowered and the material was discharged to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value was 60.7mg KOH / g. According to the specific embodiment of the present invention, it was prepared into a polyurethane elastomer, and the product oxygen index was 27.9%, and the elastomer tensile strength was 43.7MPa.

[0039] [Example 3]

[0040] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 3.8kg of 2,5-pyridinediol, 4.5kg of diethyl carbonate, and 2.2kg of triethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 25ppm of triethylamine accounting for the total mass of the above raw materials was added as a catalyst. The reaction was started, and the temperature was raised to 190°C under normal pressure and then kept warm for 8h, and then evacuated to 3kPa, and the reaction was continued for 14h, and the temperature was lowered and the material was discharged to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value was 61.8mgKOH / g. According to the specific embodiment of the present invention, it was prepared into a polyurethane elastomer with an oxygen index of 28.2% and an elastomer tensile strength of 45.5MPa.

[0041] [Example 4]

[0042] In a 15L stainless steel reactor equipped with a stirrer, heater, condenser, thermocouple, and distillation column, 3.5kg of 2,2'-bipyridine-3,3'-diol, 4.5kg of ethyl methyl carbonate, and 2.3kg of triethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 125ppm of tetraisopropyl titanate accounting for the total mass of the above raw materials was added as a catalyst. Start the reaction, heat to 190°C under normal pressure, keep warm for 7h, evacuate to 1kPa, continue to react for 12h, cool down, and discharge to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value is 62.5mg KOH / g. According to the specific embodiment of the present invention, it is prepared into a polyurethane elastomer with an oxygen index of 28.5% and an elastomer tensile strength of 46.8MPa.

[0043] [Example 5]

[0044] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 4.5kg of 2,3-pyridinediol, 5kg of dimethyl carbonate, and 2.1kg of diethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 150ppm of tetrabutyl titanate accounting for the total mass of the above raw materials was added as a catalyst. The reaction was started, and the temperature was raised to 210°C under normal pressure and then kept warm for 7h, and then evacuated to 5kPa, and the reaction was continued for 12h, and the temperature was lowered and the material was discharged to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value was 61.2mg KOH / g, and it was prepared into a polyurethane elastomer according to the specific embodiment of the present invention, with an oxygen index of 28.8% and an elastomer tensile strength of 45.9MPa.

[0045] [Example 6]

[0046] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 4.5kg of 2,4-pyridinediol, 4.4kg of diphenyl carbonate, and 1.7kg of diethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 140ppm of tetraisopropyl titanate accounting for the total mass of the above raw materials was added as a catalyst. The reaction was started, and the temperature was raised to 200°C under normal pressure and then kept warm for 6h, and then evacuated to 5kPa, and the reaction was continued for 14h, and the temperature was lowered and the material was discharged to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value was 62.2mg KOH / g. According to the specific embodiment of the present invention, it was prepared into a polyurethane elastomer with an oxygen index of 29.2% and an elastomer tensile strength of 48.2MPa.

[0047] [Comparative Example]

[0048] In a 15L stainless steel reactor equipped with a stirrer, a heater, a condenser, a thermocouple, and a distillation column, 3.5kg of triethylene glycol, 5kg of dimethyl carbonate, and 1.5kg of diethylene glycol were added in sequence under nitrogen protection and stirring conditions, and 130ppm of tetrabutyl titanate accounting for the total mass of the above raw materials was added as a catalyst. The reaction was started, and the temperature was raised to 210°C under normal pressure and then kept warm for 8h, and then evacuated to 5kPa, and the reaction was continued for 12h, and the temperature was lowered and the material was discharged to obtain a flame-retardant polycarbonate polyol. After testing, the hydroxyl value was 62.5mgKOH / g, and it was prepared into a polyurethane elastomer according to the specific implementation method of the present invention, with an oxygen index of 25.6% and an elastomer tensile strength of 36.4MPa.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a flame retardant polycarbonate polyol, characterized in that: Using pyridine diol or bipyridine diol, small molecular carbonate and other diols as raw materials, polycondensation reaction is carried out in the presence of a catalyst to generate polycarbonate polyol; Taking the total mass of the following raw materials as 100%, the mass proportions of each substance are: Pyridine diol or bipyridine diol 20-50%, Small molecule carbonate 30-70%, Other glycols 10-30%.

2. The preparation method according to claim 1, characterized in that: In the reaction system, taking the total mass of the following raw materials as 100%, the mass proportions of each substance are: Pyridine diol or bipyridine diol 25-45%, Small molecule carbonate 35-55%, Other glycols 15-25%.

3. The preparation method according to claim 1, characterized in that: The amount of the catalyst used is 100-200 ppm of the total mass of the raw materials.

4. The preparation method according to claim 3, characterized in that: The amount of the catalyst used is 20-150 ppm based on the total mass of the raw materials.

5. The preparation method according to claim 1, characterized in that: The catalyst is one or more of tetrabutyl titanate, tetraisopropyl titanate, dibutyltin dilaurate, stannous octoate, dibutyltin octoate, trimethylamine, triethylamine, tripropylamine, and p-toluenesulfonic acid.

6. The preparation method according to claim 5, characterized in that: The catalyst is tetrabutyl titanate.

7. The preparation method according to claim 1, characterized in that: The pyridine diol or bipyridine diol is one or more of 2,3-pyridine diol, 2,4-pyridine diol, 2,5-pyridine diol, 2,2'-bipyridine-3,3'-diol, 2,2'-bipyridine-5,5'-diol and 2,2'-bipyridine-4,4'-diol.

8. The preparation method according to claim 7, characterized in that: The pyridine diol or bipyridine diol is 2,2'-bipyridine-3,3'-diol.

9. The preparation method according to claim 1, characterized in that: The other diols are selected from one or more of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propylene glycol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol.

10. The preparation method according to claim 9, characterized in that: The other diols are one or more of diethylene glycol and triethylene glycol.

11. The preparation method according to claim 1, characterized in that: The small molecule carbonate is one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate and diphenyl carbonate.

12. The preparation method according to claim 1, characterized in that: The preparation method of the polycarbonate polyol adopts a batch process, and the reactor adopts a kettle reactor.

13. The preparation method according to claim 1, characterized in that: In a nitrogen atmosphere, various raw materials are added, and the temperature is raised to 160-250°C under normal pressure. After the reaction is kept at normal pressure for a period of time, the reaction is continued by vacuuming until the hydroxyl value of the product reaches the designed hydroxyl value ±10mg KOH / g, and then the reaction is stopped.

14. The preparation method according to claim 13, characterized in that: In a nitrogen atmosphere, various raw materials were added and the temperature was raised to 180-210°C under normal pressure.

15. The preparation method according to claim 13, characterized in that: The reaction time at normal pressure is 5-10h.

16. The preparation method according to claim 15, characterized in that: The reaction time at normal pressure is 6-8h.

17. The preparation method according to claim 13, characterized in that: The reaction time under vacuum conditions is 5-10 hours, and the vacuum conditions are an absolute pressure of 1-10 kPa.

18. The preparation method according to claim 17, characterized in that: The reaction time under vacuum conditions is 10-15 hours, and the vacuum conditions are an absolute pressure of 1-5 kPa.

19. Use of the polycarbonate polyol prepared by the preparation method according to any one of claims 1 to 18, wherein the polycarbonate polyol is used for preparing a polyurethane elastomer.

20. The use according to claim 19, wherein the polyurethane elastomer comprises the following raw material components in parts by weight: 25-35 parts of isocyanate, 5-9 parts of chain extender, 50-60 parts of polycarbonate polyol, 2-5 parts of antioxidant and 0.4-2 parts of catalyst.