Aromatic polyester polyol, raw material composition, polyurethane foam and preparation method

Abstract

The invention discloses aromatic polyester polyol, a raw material composition, polyurethane foam and a preparation method. The aromatic polyester polyol comprises the following raw material components: phthalic anhydride, diethylene glycol, a catalyst and aromatic diacid, the molar ratio of the phthalic anhydride and the aromatic diacid to the diethylene glycol is 1: (1.7-2.2), and the molar ratio of the phthalic anhydride to the 2, 6-naphthalic acid is (10-1): 1. The aromatic polyester polyol disclosed by the invention is moderate in raw material price and relatively low in cost; the preparation method is simple, mild in reaction condition, convenient to operate, energy-saving and environment-friendly; the aromatic polyester polyol prepared from the aromatic diacid has good compatibility with isopentane and good thermal stability; the polyurethane foam disclosed by the invention is high in compression strength, excellent in flame retardant property and good in high-temperature dimensional stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to an aromatic polyester polyol, a polyurethane raw material composition containing the polyester polyol, a high-performance polyurethane foam prepared from the composition and a preparation method thereof. BACKGROUND

[0002] Polyurethane, abbreviated as PU, is an elastomer high polymer material composed of hard segments and soft segments, and is a commonly used foaming material. The performance of polyurethane foam is highly dependent on the structural characteristics of the polyol. Traditional aromatic polyurethane foam often uses a polyester polyol system based on phthalic anhydride, which is obtained by polycondensation of phthalic acid and diols (such as diethylene glycol). The benzene ring structure in the molecular chain of such a polyol endows the foam with certain rigidity, heat resistance and cost advantage, and is widely used in the field of hard or semi-hard foam.

[0003] At present, the research on polyester-type PU at home and abroad shows that the foam plastic prepared by foaming aromatic polyester-type PU has high strength, good toughness, low thermal conductivity and excellent flame retardance. However, with the improvement of the performance requirements of application scenarios on materials (such as high-temperature stability, mechanical strength and environmental friendliness), the patent with publication number US005109031A discloses that the traditional single acid-based polyol system gradually exposes the following limitations: the benzene ring structure of the phthalic acid-based polyol enhances the rigidity, but the flexibility of the molecular chain is insufficient, leading to an increase in the brittleness of the foam, which is prone to cracking, especially under low temperature or dynamic load; the upper limit of the heat resistance of the single benzene ring structure is relatively low (usually lower than 200℃), and the chain segment is prone to thermal decomposition in a high-temperature environment, which limits its application in high-temperature scenarios such as automobile engine compartments and electronic packaging; phthalic acid is a dibasic acid, and the polyol obtained by polycondensation of phthalic acid and diethylene glycol has a low functionality, which limits the crosslinking density with isocyanate, affecting the size stability and closed cell rate control of the foam. In view of the high conjugation effect and excellent thermal stability of the naphthalene ring structure, the polyethylene naphthalate (PEN) prepared by using naphthalene dicarboxylic acid as a monomer has excellent performance in barrier properties, heat resistance, modulus, size stability and chemical resistance. The patent with publication number CN119968409A discloses that the introduction of a cyclic structure into the polyol is beneficial to the improvement of stability. Therefore, how to design the molecular structure and innovate the process to introduce the naphthalene ring structure while retaining the cost advantage of the phthalic acid system, break through the performance bottleneck, and realize the synergistic effect of the two types of acid components has become a technical problem to be solved in the field. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the existing aromatic polyester polyol reaction rate, side reaction inhibition, acid value control and performance upper limit, and to provide an aromatic polyester polyol, a raw material composition, a polyurethane foam and a preparation method.

[0005] The present application solves the above technical problems through the following technical solutions.

[0006] The present application provides a raw material composition of an aromatic polyester polyol, which comprises the following raw material components: phthalic anhydride, diethylene glycol, naphthalene dicarboxylic acid and a catalyst. Among them, the naphthalene dicarboxylic acid is 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid or 1,8-naphthalene dicarboxylic acid; the molar ratio of the mixed acid (phthalic anhydride and naphthalene dicarboxylic acid) to the diethylene glycol is 1:(1.7~2.2); the molar ratio of the phthalic anhydride to the naphthalene dicarboxylic acid is (0.4~6.0):1.

[0007] In the present application, the phthalic anhydride and the diethylene glycol are both industrial grade reagents.

[0008] In the present application, the aromatic diacid is preferably one or more of 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid and 1,8-naphthalene dicarboxylic acid, and more preferably 1,4-naphthalene dicarboxylic acid; wherein the 1,4-naphthalene dicarboxylic acid, the 2,6-naphthalene dicarboxylic acid and the 1,8-naphthalene dicarboxylic acid are all industrial grade reagents.

[0009] In the present application, the molar ratio of (phthalic anhydride and naphthalene dicarboxylic acid) to diethylene glycol is 1:(1.7~2.2).

[0010] In the present application, the molar ratio of the phthalic anhydride to the naphthalene dicarboxylic acid is preferably (0.4~6.0):1, and more preferably 5:1.

[0011] In the present application, the catalyst can be a catalyst commonly used in such esterification reactions in the art, and more preferably is isopropyl titanate.

[0012] In the present application, the amount of the catalyst can be a conventional amount in the art, and preferably is 0.01~0.04% of the total mass of the phthalic anhydride, the diethylene glycol and the naphthalene dicarboxylic acid, and more preferably is 0.02~0.03% of the total mass of the monomers. The total mass of the monomers is the total mass of the phthalic anhydride, the diethylene glycol and the naphthalene dicarboxylic acid.

[0013] The present application provides a preparation method of aromatic polyester polyol, which comprises the following steps: After the esterification reaction of the phthalic anhydride, diethylene glycol, naphthalene dicarboxylic acid and catalyst, the system is cooled, and after-treatment is performed to obtain the aromatic polyester polyol.

[0014] In the present application, the operation and conditions of the esterification reaction can be conventional operation and conditions in the art.

[0015] In the present application, the temperature of the esterification reaction can be conventional, preferably 180-230℃, more preferably 220-225℃.

[0016] In the present application, the time of the esterification reaction can be conventional, preferably 3-7h, more preferably 4-6h, most preferably 4.5-5h.

[0017] In the present application, after the cooling, the temperature of the system can be conventional, preferably 130-170℃, more preferably 150-160℃.

[0018] In the present application, the operation and conditions of the after-treatment can be conventional operation and conditions in the art, preferably drying. The operation and conditions of the drying can be conventional operation and conditions in the art, generally vacuum drying. After the operation of the after-treatment, water and excess alcohol in the system can be removed.

[0019] Preferably, the vacuum time is 2-6h, more preferably 3-4h.

[0020] The present application also provides an aromatic polyester polyol prepared by the above preparation method.

[0021] The present application also provides an aromatic polyurethane foam raw material composition, which comprises the aromatic polyester polyol, isocyanate and isopentane.

[0022] Preferably, the isocyanate is aromatic isocyanate or aliphatic isocyanate in the art, more preferably aromatic diisocyanate, most preferably toluene diisocyanate (TDI) and / or 4,4'-methylene bis(phenyl isocyanate) (MDI).

[0023] Preferably, the mass ratio of the aromatic polyester polyol to the isocyanate can be selected according to conventional methods in the art, preferably (1.1:0.9)-(1.2:1.5), more preferably (1.2:1.1)-(1.2:1.3).

[0024] The amount of isopentane can be selected according to conventional methods in the art, preferably 8-12% by mass of the total amount of the aromatic polyester polyol and the isocyanate, more preferably 10% by mass of the total amount of the aromatic polyester polyol and the isocyanate.

[0025] The present application also provides a method for preparing an aromatic polyurethane foam, which comprises the following steps: mixing the aromatic polyurethane raw material composition, and foaming.

[0026] The mixing operation and conditions can be conventional mixing operation and conditions in the art.

[0027] The foaming operation and conditions can be conventional foaming operation and conditions in the art. The foaming temperature is preferably 36-40°C. The foaming molding time is preferably 9-12 min.

[0028] After the aromatic polyurethane foam is foamed and molded, it is allowed to mature in an environment at 22-26°C for 24 h, preferably in an environment at 23-25°C for 24 h.

[0029] The present application also provides an aromatic polyurethane foam prepared by the above method.

[0030] On the basis of common sense in the art, the above preferred conditions can be combined arbitrarily, thereby obtaining various preferred examples of the present application.

[0031] The reagents and raw materials used in the present application are commercially available.

[0032] The present application has the following advantages: (1) The raw materials used in the present application are moderately priced and cost-effective. (2) The reaction conditions are relatively mild, the process is simple, the operation is convenient, and the process is energy-saving and environmentally friendly. (3) The aromatic polyester polyol of the present application has good compatibility with isopentane. The polyurethane foam of the present application has high strength, good flame retardancy, and good high-temperature dimensional stability. The compressive strength of the polyurethane foam material in the vertical direction is 382-465 KPa, the compressive strength perpendicular to the growth direction 1 of the foam is 225-329 KPa, the compressive strength perpendicular to the growth direction 2 of the foam is 180-329 KPa, the oxygen index is 25.8-31.6%, and the high-temperature dimensional stability is long: 0.02-0.06%, wide: 0.02-0.06%, and high: 0.02-0.06%. DETAILED DESCRIPTION

[0033] The present application is further illustrated by the following examples, but the present application is not limited to the examples. The experimental methods in the following examples, for which no specific conditions are indicated, are selected according to conventional methods and conditions, or according to the instructions of the commercial products.

[0034] In the following examples: The industry standard for polyurethane foam compressive strength is to cut the foam into 5x5x5 cm cubes and then test on a universal pressure testing machine. The industry standard for oxygen index is to cut the polyurethane foam into 1x1x10 cm samples and then test on a limiting oxygen index machine. The compatibility of the polyester polyol with isopentane is characterized by the method conventional in the art, which is to place the polyester and isopentane in a mass ratio of 5:1 for one day to see if they are layered. The specific operation for determining the acid value is to dissolve about 3 g of the polyester with a pyridine solution, titrate with a potassium hydroxide standard solution, and finally multiply the volume of consumed potassium hydroxide by the molar volume of the standard solution and divide by the mass of the polyester. The specific operation for determining the viscosity is to test with a cone and plate viscometer at 25°C, with a No. 3 rotor, and 30 revolutions. The standard for testing the hydroxyl value is GB 12008.3-89. The standard for testing the high-temperature dimensional stability is GB 8811-88.

[0035] Example 1 Preparation of aromatic polyester polyol: A three-necked flask is connected with a water separator, a stirring rod, and a thermometer, respectively. Under the protection of N2 atmosphere, 126.96 g of phthalic anhydride, 212.24 g of diethylene glycol, 30.88 g of 1,4-naphthalene dicarboxylic acid, and a catalyst are added to the four-necked flask, wherein the molar ratio of the above three monomers is phthalic anhydride: diethylene glycol: 1,4-naphthalene dicarboxylic acid = 0.6:1:0.1, and the mass percentage of the catalyst is 0.02%. The temperature is raised to the melting point of the monomers, and stirring is started. The temperature is maintained at about 220°C for 4.5 h, and then the temperature is lowered to 160°C and vacuumized for 3 h to obtain the product.

[0036] Preparation of aromatic polyurethane: The aromatic polyurethane raw material composition is mixed, wherein the mass ratio of the aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) is 1.0:0.8, and the mass percentage of isopentane is 10%. The above-mentioned aromatic polyurethane raw material composition is foamed, the foaming temperature is 38°C, 10 min, and the curing is carried out at 25°C for 24 h.

[0037] The polyester polyol has an acid value of 0.53 mg KOH / g, a viscosity of 3858 mPa.s, a hydroxyl value of 266.53 mg KOH / g, and good compatibility with isopentane in a mass ratio of 5:1. The compressive strength of the polyurethane foam material is 432 KPa in the vertical direction, 315 KPa in the direction perpendicular to the growth direction of the foam, 311 KPa in the direction perpendicular to the growth direction of the foam, the oxygen index is 25.5%, and the high-temperature dimensional stability is 0.03% in length, 0.03% in width, and 0.03% in height.

[0038] Example 2 Preparation of aromatic polyester polyol: Three-necked flask was connected with water separator, stirring rod and thermometer respectively. 123.43 g phthalic anhydride, 212.24 g diethylene glycol, 36.03 g 1,4-naphthalene dicarboxylic acid and catalyst were added into the four-necked flask respectively under the protection of N2 atmosphere, wherein the molar ratio of the above three monomers was phthalic anhydride: diethylene glycol: 1,4-naphthalene dicarboxylic acid = 0.5:1:0.1, and the mass percentage of catalyst was 0.02%. The temperature was raised to the melting point of monomers, and then the stirring was started. The reaction was carried out at about 220℃ for 4.5 h, and then the temperature was lowered to 160℃ and vacuumized for 3 h to obtain the product.

[0039] Preparation of aromatic polyurethane: The aromatic polyurethane raw material composition was mixed, wherein the mass ratio of aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) was 1.0:0.8, and the mass percentage of isopentane was 10%. The above-mentioned aromatic polyurethane raw material composition was foamed, the foaming temperature was 38℃, 10 min, and the curing was carried out at 25℃ for 24 h.

[0040] The polyester polyol had an acid value of 0.46 mg KOH / g, a viscosity of 4387 mPa.s, a hydroxyl value of 262.79 mg KOH / g, and good compatibility with isopentane at a mass ratio of 5:1. The compressive strength of the polyurethane foam material was 465 KPa in the vertical direction, 329 KPa in the direction perpendicular to the growth direction of the foam, 327 KPa in the direction perpendicular to the growth direction of the foam, the oxygen index was 25.5%, and the high-temperature dimensional stability was 0.02% in length, 0.02% in width, and 0.02% in height.

[0041] Example 3 Preparation of aromatic polyester polyol: Three-necked flask was connected with water separator, stirring rod and thermometer respectively. 123.43 g phthalic anhydride, 212.24 g diethylene glycol, 36.03 g 1,4-naphthalene dicarboxylic acid and catalyst were added into the four-necked flask respectively under the protection of N2 atmosphere, wherein the molar ratio of the above three monomers was phthalic anhydride: diethylene glycol: 1,4-naphthalene dicarboxylic acid = 0.5:1:0.1, and the mass percentage of catalyst was 0.02%. The temperature was raised to the melting point of monomers, and then the stirring was started. The reaction was carried out at about 220℃ for 4.5 h, and then the temperature was lowered to 160℃ and vacuumized for 3 h to obtain the product.

[0042] Preparation of aromatic polyurethane: The aromatic polyurethane raw material composition was mixed, wherein the mass ratio of aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) was 1.0:0.8, and the mass percentage of isopentane was 10%. The above-mentioned aromatic polyurethane raw material composition was foamed, the foaming temperature was 38℃, 10 min, and the curing was carried out at 25℃ for 24 h.

[0043] The polyester polyol has an acid value of 0.55 mg KOH / g, a viscosity of 8546 mPa.s, a hydroxyl value of 252.89 mg KOH / g, and good compatibility with isopentane at a mass ratio of 5:1. The compressive strength of the polyurethane foam material is 436 KPa in the vertical direction, 302 KPa in the direction perpendicular to the growth direction of the foam, 295 KPa in the direction perpendicular to the growth direction of the foam, the oxygen index is 26.4%, and the high-temperature dimensional stability is 0.05% in length, 0.03% in width, and 0.04% in height.

[0044] [Example 4] Preparation of the aromatic polyester polyol: A three-necked flask is connected with a water separator, a stirring rod, and a thermometer, respectively. 74.06 g of phthalic anhydride, 212.24 g of diethylene glycol, 108.095 g of 1,4-naphthalene dicarboxylic acid, and a catalyst are added to the four-necked flask under the protection of N2 atmosphere, wherein the molar ratio of the three monomers is phthalic anhydride: diethylene glycol: 1,4-naphthalene dicarboxylic acid = 0.25:1:0.25, and the mass percentage of the catalyst is 0.02%. The temperature is raised to the melting point of the monomers, and stirring is started. The temperature is maintained at about 220°C for 4.5 h, and then the temperature is lowered to 160°C and vacuumized for 3 h to obtain the aromatic polyester polyol.

[0045] Preparation of the aromatic polyurethane: The aromatic polyurethane raw material composition is mixed, wherein the mass ratio of the aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) is 1.0:0.9, and the mass percentage of isopentane is 10%. The aromatic polyurethane raw material composition is foamed at a foaming temperature of 38°C for 10 min, and then cured at 25°C for 24 h.

[0046] The polyester polyol has an acid value of 0.58 mg KOH / g, a viscosity of 9567 mPa.s, a hydroxyl value of 253.79 mg KOH / g, and good compatibility with isopentane at a mass ratio of 5:1. The compressive strength of the polyurethane foam material is 436 KPa in the vertical direction, 302 KPa in the direction perpendicular to the growth direction of the foam, 295 KPa in the direction perpendicular to the growth direction of the foam, the oxygen index is 26.4%, and the high-temperature dimensional stability is 0.05% in length, 0.03% in width, and 0.04% in height.

[0047] [Example 5] Preparation of aromatic polyester polyol: Three-necked flask was connected with water separator, stirring rod and thermometer respectively. 59.248 g phthalic anhydride, 212.24 g diethylene glycol, 129.714 g 1,4-naphthalene dicarboxylic acid and catalyst were added into the four-necked flask respectively under the protection of N2 atmosphere, wherein the molar ratio of the above three monomers was phthalic anhydride: diethylene glycol: 1,4-naphthalene dicarboxylic acid = 0.2:1:0.3, and the mass percentage of catalyst was 0.025%. The temperature was raised to the melting point of monomers, and then the stirring was started. The reaction was carried out at about 220°C for 4.5 h, and then the temperature was lowered to 160°C and vacuumized for 3 h to obtain the product.

[0048] Preparation of aromatic polyurethane: The aromatic polyurethane raw material composition was mixed, wherein the mass ratio of aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) was 1.0:1.1, and the mass percentage of isopentane was 10%. The above-mentioned aromatic polyurethane raw material composition was foamed, the foaming temperature was 38°C, 10 min, and the curing was carried out at 25°C for 24 h.

[0049] The polyester polyol had an acid value of 0.51 mg KOH / g, a viscosity of 10557 mPa.s, a hydroxyl value of 259.82 mg KOH / g, and good compatibility with isopentane at a mass ratio of 5:1. The compressive strength of the polyurethane foam material was 391 KPa in the vertical direction, 237 KPa in the direction perpendicular to the growth direction of the foam, 215 KPa in the direction perpendicular to the growth direction of the foam, the oxygen index was 30.4%, and the high-temperature dimensional stability was 0.06% in length, 0.06% in width, and 0.04% in height.

[0050]

Example 6

[0051] Preparation of aromatic polyurethane: The aromatic polyurethane raw material composition was mixed, wherein the mass ratio of aromatic polyester polyol to 4,4'-methylene bis(phenyl isocyanate) (MDI) was 1.0:1.1, and the mass percentage of isopentane was 10%. The above-mentioned aromatic polyurethane raw material composition was foamed, the foaming temperature was 38°C, 10 min, and the curing was carried out at 25°C for 24 h.

[0052] The polyester polyol has an acid value of 0.44 mg KOH / g, a viscosity of 11587 mPa.s, a hydroxyl value of 255.82 mg KOH / g, and good compatibility with isopentane in a mass ratio of 5:1. The compressive strength of the polyurethane foam material is 380 KPa in the vertical direction, 225 KPa perpendicular to the growth direction of the foam 1, 180 KPa perpendicular to the growth direction of the foam 2, the oxygen index is 31.6%, and the high-temperature dimensional stability is 0.06% in length, 0.04% in width, and 0.05% in height.

[0053] Table 1 Performance data and performance change degree of pure phthalic anhydride system and mixed acid system

[0054] The pure phthalic anhydride system data come from CN 108690187 A. Compared with the pure phthalic anhydride system, the vertical strength of the polyurethane rigid foam with the addition of 1,4-naphthalene dicarboxylic acid is increased by 14-39%, the compressive strength in the vertical direction 1 and the vertical direction 2 is increased by 15-45%, the flame retardant performance is also improved, and the high-temperature stability is slightly improved.

Claims

1. A raw material composition for an aromatic polyester polyol, characterized in that, It comprises the following raw material components: phthalic anhydride, diethylene glycol, naphthalic acid, and a catalyst; wherein the naphthalic acid is 1,4-naphthalic acid, 2,6-naphthalic acid, or 1,8-naphthalic acid; the molar ratio of the mixed acid (phthalic anhydride and naphthalic acid) to the diethylene glycol is 1:(1.7~2.2); and the molar ratio of the phthalic anhydride to the naphthalic acid is (0.4~6.0):

1.

2. The raw material composition according to claim 1, characterized in that, The naphthalenedicarboxylic acid is one or more of 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 1,8-naphthalenedicarboxylic acid, more preferably 1,4-naphthalenedicarboxylic acid; The molar ratio of phthalic anhydride and naphthalenedicarboxylic acid to diethylene glycol is 1:(1.7~2.2); The molar ratio of phthalic anhydride to naphthalic acid is (0.4~6.0):1, more preferably 5:1; The catalyst may be a conventional catalyst used in this type of esterification reaction, and more preferably isopropyl titanate. And / or, the amount of the catalyst is 0.01 to 0.04% of the total mass of the monomers, more preferably 0.02 to 0.03% of the total mass of the monomers, wherein the total mass of the monomers is the total mass of the three monomers: phthalic anhydride, diethylene glycol, and naphthalic acid.

3. A method for preparing an aromatic polyester polyol, characterized in that, It includes the following steps: subjecting the phthalic anhydride, diethylene glycol, naphthalic acid and catalyst as described in claim 1 or 2 to an esterification reaction, cooling, and then performing post-treatment to obtain the product.

4. The preparation method according to claim 3, characterized in that, The esterification reaction is preferably carried out at a temperature of 180~230℃, more preferably at 220~225℃; The esterification reaction is preferably carried out for 3 to 7 hours, more preferably for 4 to 6 hours, and most preferably for 4.5 to 5 hours. After the cooling process, the system temperature is preferably 130~170℃, more preferably 150~160℃; And / or, the post-processing is drying, the drying is vacuum drying, and the vacuum drying time is preferably 2-6 hours, more preferably 3-4 hours.

5. An aromatic polyester polyol prepared by the method described in claim 3 or 4.

6. A raw material composition for an aromatic polyurethane foam, characterized in that, It includes the aromatic polyester polyol, isocyanate and isopentane as described in claim 5.

7. The raw material composition according to claim 6, characterized in that, The isocyanate is an aromatic isocyanate and / or an aliphatic isocyanate, preferably an aromatic diisocyanate, more preferably toluene diisocyanate and / or 4,4'-methylenebis(phenyl isocyanate); The preferred mass ratio of the aromatic polyester polyol to the isocyanate is (1.1:0.9) to (1.2:1.5), more preferably (1.2:1.1) to (1.2:1.3); And / or, the amount of isopentane is preferably 8-12% of the total mass of the aromatic polyester polyol and the isocyanate, more preferably 10% of the total mass of the aromatic polyester polyol and the isocyanate.

8. A method for preparing aromatic polyurethane foam, characterized in that, It includes the following steps: mixing the aromatic polyurethane raw material composition as described in claim 6 or 7, and foaming it.

9. The preparation method according to claim 8, characterized in that, The foaming temperature is 36~40℃, and the foaming molding time is 9~12min; And / or, after the aromatic polyurethane foam is foamed and molded, it is cured at 22~26℃ for 24 hours, preferably at 23~25℃ for 24 hours.

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