An additive for reducing the crystallization point of polyester-modified MDI, and a preparation method and application thereof

Abstract

The application provides an additive for reducing the crystallization point of polyester modified MDI, a preparation method and application thereof. The additive is prepared from the following components in parts by weight: 100 parts of first polyester polyol, 14.8-44.4 parts of diisocyanate, 8.7-26 parts of mono-alcohol compound, and 0-0.1 parts of catalyst. The additive can not only reduce the crystallization temperature of polyester modified MDI, but also is beneficial to the mass production of polyurethane microporous elastomer. Compared with the conventional product disclosed in the prior art, the additive can reduce the preheating time in the later application and ensure that the product has good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of additive materials technology, specifically relating to an additive for reducing the crystallization point of polyester-modified MDI, its preparation method, and its application. Background Technology

[0002] Polyester-modified MDI is widely used in the production of polyurethane microporous elastomers, especially in the fields of polyurethane shoe soles and polyurethane foamed tires. Polyurethane microporous shoe soles are produced by foaming a polyol component (A) with a modified isocyanate component (B), where component B is often polyester-modified MDI. In practical applications, it has been found that polyester-modified MDI has a high crystallization point temperature and is prone to crystallization at ambient temperatures below 20°C. Therefore, it requires heating and melting during use, significantly prolonging the preheating time of the raw materials, increasing energy consumption, and reducing production efficiency. Furthermore, researchers have found that if the storage temperature of polyester-modified MDI fluctuates around its crystallization point, it is prone to generating dimer impurities, which significantly shortens the shelf life and thus affects the overall performance of the product.

[0003] Existing technologies disclose the addition of additives to lower the crystallization point of polyester-modified MDI. For example, CN104761883A discloses a method of adding γ-butyrolactone and diisooctyl adipate to lower the freezing point. Although this method can achieve certain effects, it pollutes the environment. CN113698565A discloses a method of adding the environmentally friendly plasticizer trihexyl acetyl citrate in two steps during the synthesis of polyester-modified MDI to lower its crystallization point. Although trihexyl acetyl citrate has a relatively small impact on the environment, due to its small relative molecular weight, when its addition amount is high, it is not only easy to precipitate, but it also reduces the mechanical properties of the product.

[0004] Therefore, there is an urgent need in this field to develop an additive that lowers the crystallization point of polyester-modified MDI in order to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an additive for lowering the crystallization point of polyester-modified MDI, its preparation method, and its application. This invention utilizes the aforementioned additive to not only lower the crystallization temperature of polyester-modified MDI, which is beneficial for the large-scale production of polyurethane microporous elastomers, but also, compared to conventional products disclosed in the prior art, reduces the preheating time for later applications and ensures that the finished product possesses good mechanical properties.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an additive for reducing the crystallization point of polyester-modified MDI, wherein the raw materials for preparing the additive comprise the following components in parts by weight:

[0008]

[0009] To address the technical problems of existing additives for reducing the crystallization point of polyester-modified MDI, such as easy precipitation, instability, and negative impact on the mechanical properties of the product, the additive provided by this invention uses a first polyester polyol, a diisocyanate, and a monool compound as raw materials to obtain a plasticizer-like compound in which both hydroxyl and isocyanate groups are fully reacted, thereby reducing the crystallinity of the resin molecules. Simultaneously, the molecular weight of the above-mentioned additive is higher than that of conventional plasticizers in the prior art, making it less prone to precipitation in the product and ensuring its stability. Furthermore, the above-mentioned additive contains a large number of side group structures, exhibiting good compatibility with other components in the modified MDI system, thus effectively reducing its crystallinity.

[0010] This invention controls the content of each component to ensure that both hydroxyl and isocyanate groups react completely, while minimizing the amount of small molecules without polyester structure. If the amount of isocyanate is too low, excess hydroxyl groups will not react and will participate in the subsequent synthesis reaction of MDI prepolymer, affecting the performance of the product. Conversely, if the amount of isocyanate is too high, more monools are needed for end-capping, generating more small molecules without polyester structure, which increases the risk of subsequent precipitation.

[0011] It should be noted that the MDI used in this invention to reduce the crystallization point of polyester-modified MDI refers to 4,4'-diphenylmethane diisocyanate.

[0012] In this invention, the weight parts of the diisocyanate are 14.8 to 44.4 parts, for example, 14.8 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, 44.4 parts, etc., and the weight parts of the diisocyanate will be adjusted according to the molecular weight of each component.

[0013] In this invention, the weight parts of the monool compound are 8.7 to 26 parts, for example, 8.7 parts, 9 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, etc., and the weight parts of the monool compound are adjusted according to the amount of diisocyanate used and its own molecular weight.

[0014] In this invention, the catalyst is 0 to 0.1 parts by weight, for example, 0 parts, 0.01 parts, 0.02 parts, 0.05 parts, 0.08 parts, 0.1 parts, etc., and the catalyst weight is adjusted according to the reactivity of the hydroxyl and isocyanate groups.

[0015] Preferably, the raw materials for preparing the additive include the following components in parts by weight:

[0016]

[0017] Preferably, the functionality of the first polyester polyol is 2.

[0018] Preferably, the first polyester polyol is prepared by copolymerizing a diol compound with side groups and adipic acid.

[0019] Preferably, the side group of the diol compound having a side group includes at least one of methyl, ethyl, butyl or phenyl, preferably methyl.

[0020] In this invention, diol compounds with specific types of side groups are used to make the first polyester polyol have the weakest possible crystallinity, but good compatibility with polyester polyols with other structures.

[0021] Preferably, the diol compound having a side group includes any one or a combination of at least two of 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol or 3-methyl-1,5-pentanediol, preferably 2-methyl-1,3-propanediol and / or 3-methyl-1,5-pentanediol.

[0022] Preferably, the number average molecular weight of the first polyester polyol is 700–5000 g / mol, more preferably 1000–2000, for example, it can be 700 g / mol, 800 g / mol, 900 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, 3500 g / mol, or 4000 g / mol. / mol, 4500g / mol, 5000g / mol, etc. It should be noted that in the field of polyurethane synthesis, the molecular weight of polyester polyols commonly used is 500-5000g / mol. However, in this invention, using polyester polyols with too low a molecular weight will result in excessive polarity of the additive, which is not conducive to improving the compatibility in the later stages. On the other hand, using polyester polyols with too high a molecular weight will result in high viscosity of the additive and affect the subsequent processing of the product. Therefore, the preferred polyester polyol in this invention is one with a number average molecular weight of 1000-2000g / mol.

[0023] Preferably, the freezing point of the diisocyanate is not higher than 10°C, and more preferably not higher than -50°C, for example, it can be -67°C, -60°C, -50°C, etc.

[0024] In this invention, it is necessary to select diisocyanates with a low freezing point as much as possible, because a freezing point that is too high will cause the synthesized additives to have a stronger crystallization ability, thereby affecting the subsequent effects.

[0025] Preferably, the diisocyanate includes any one or a combination of at least two of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), or toluene diisocyanate (TDI-65), and is more preferably isophorone diisocyanate and / or hexamethylene diisocyanate.

[0026] Preferably, the monool compound includes monool compounds having side groups.

[0027] Preferably, the side groups of the primary alcohol compounds having side groups include alkyl groups, preferably ethyl groups.

[0028] In this invention, monool compounds with specific types of side groups are used to minimize the crystallinity of the synthesized additive. Using monool compounds with larger side groups (such as phenyl) would reduce the mobility of the additive's molecular chains, thus decreasing subsequent compatibility. It should also be noted that because the specific types of first polyester polyols and diisocyanates with specific freezing points provided in this invention have a significant effect on reducing crystallinity, in some cases, even monool compounds without side groups can be used to reduce the crystallinity of polyester-modified MDI.

[0029] Preferably, the monool compound having a side group includes any one or a combination of at least two of 2-ethylhexanol, isopropanol, or isobutanol, with 2-ethylhexanol being the most preferred.

[0030] Preferably, the catalyst comprises an organotin catalyst.

[0031] Preferably, the organotin catalyst comprises dibutyltin dilaurate and / or stannous octoate.

[0032] In a second aspect, the present invention provides a method for preparing an additive according to the first aspect for reducing the crystallization point of polyester-modified MDI, the method comprising the following steps:

[0033] (1) The first polyester polyol, diisocyanate and optional catalyst are reacted according to the formula to obtain the prepolymer;

[0034] (2) The prepolymer obtained in step (1) is reacted with a monool compound to obtain the additive used to reduce the crystallization point of polyester-modified MDI.

[0035] Preferably, the first polyester polyol in step (1) needs to undergo a pretreatment before the reaction.

[0036] Preferably, the pretreatment includes a dehydration process.

[0037] Preferably, the primary dehydration process is performed under vacuum.

[0038] Preferably, the temperature of the first dehydration treatment is 100-120℃, for example, 100℃, 105℃, 110℃, 115℃, 120℃, etc.; the time is 2-3h, for example, 2h, 2.2h, 2.5h, 2.8h, 3h, etc.

[0039] Preferably, the reaction in step (1) is carried out under an inert atmosphere.

[0040] Preferably, the reaction temperature in step (1) is 90-95°C, for example, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C; and the time is 3-4 hours, for example, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, or 4 hours.

[0041] Preferably, the temperature of the reaction in step (2) is 90-95°C, for example, 90°C, 91°C, 92°C, 93°C, 94°C, or 95°C; and the time is 3-4 hours, for example, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, or 4 hours.

[0042] Thirdly, the present invention provides a polyester-modified MDI, wherein the raw materials for preparing the polyester-modified MDI include the additives for reducing the crystallization point of the polyester-modified MDI as described in the first aspect, and the raw materials for preparing the polyester-modified MDI include the following components in parts by weight:

[0043]

[0044] In this invention, the second polyester polyol is 20 to 35 parts by weight, for example, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, etc.

[0045] In this invention, the weight parts of 4,4'-diphenylmethane diisocyanate are 55 to 70 parts, for example, 55 parts, 58 parts, 60 parts, 62 parts, 65 parts, 68 parts, 70 parts, etc.

[0046] In this invention, the additive used to reduce the crystallization point of polyester-modified MDI is 3 to 10 parts by weight, for example, 3, 4, 5, 6, 7, 8, 9, 10 parts, etc.

[0047] In this invention, the weight of liquefied MDI is 5 to 10 parts, for example, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0048] In this invention, the polymerization inhibitor is present in parts by weight of 0.002 to 0.01, for example, 0.002, 0.003, 0.005, 0.007, 0.008, 0.009, 0.01, etc.

[0049] In this invention, by adjusting the content of each of the above components, the content of isocyanate groups in the final polyester-modified MDI is 18-24%, preferably 20-22%. It should be noted that the content of isocyanate groups in the most commonly used polyester-modified MDI for preparing polyurethane microporous elastomers, especially shoe soles, is 20-22%.

[0050] Preferably, the raw materials for preparing the polyester-modified MDI include the following components in parts by weight:

[0051]

[0052] Preferably, the functionality of the second polyester polyol is 2.

[0053] Preferably, the second polyester polyol is prepared by copolymerizing one or more of ethylene glycol, diethylene glycol or 1,4-butanediol with adipic acid or terephthalic acid, and more preferably polyethylene glycol adipate diethylene glycol ester diol and / or polyethylene glycol adipate butylene glycol ester diol. The second polyester polyols listed above are the most commonly used polyester polyols in the prior art for preparing polyester-modified MDI.

[0054] Preferably, the number average molecular weight of the second polyester polyol is 1000-3000 g / mol, more preferably 2000 g / mol. For example, it can be 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, etc. It should be noted that polyester polyols with a molecular weight of 2000 g / mol are the most commonly used. For example, it can be polyester polyol products from Shanghai Huide Technology Co., Ltd., with model numbers HDPOL-2420 or HDPOL-2520, respectively.

[0055] Preferably, the liquefied MDI is carbodiimide-modified diphenylmethane diisocyanate.

[0056] Preferably, the polymerization inhibitor includes an inorganic acid, an organic acid, or benzoyl chloride, and is preferably benzoyl chloride.

[0057] Fourthly, the present invention provides a method for preparing polyester-modified MDI according to the third aspect, the method comprising the following steps:

[0058] (A) The second polyester polyol, 4,4'-diphenylmethane diisocyanate and the additive for reducing the crystallization point of polyester-modified MDI as described in the first aspect are reacted according to the formulation amount to obtain a prepolymer;

[0059] (B) The prepolymer obtained in step (A), liquefied MDI and polymerization inhibitor are mixed to obtain the polyester-modified MDI.

[0060] Preferably, the second polyester polyol in step (A) needs to be pretreated before the reaction.

[0061] Preferably, the pretreatment includes a dehydration process.

[0062] Preferably, the dehydration process is carried out under vacuum.

[0063] Preferably, the temperature of the dehydration treatment is 100-120℃, for example, 100℃, 105℃, 110℃, 115℃, 120℃, etc.; the time is 2-3h, for example, 2h, 2.2h, 2.5h, 2.8h, 3h, etc.

[0064] Preferably, the reaction in step (A) is carried out under an inert atmosphere.

[0065] Preferably, the temperature of the reaction in step (A) is 70-80°C, for example, 70°C, 72°C, 75°C, 78°C, or 80°C; and the time is 2-3 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, or 3 hours.

[0066] Preferably, the temperature of the reaction in step (B) is 50-60°C, for example, 50°C, 52°C, 55°C, 58°C, 60°C, etc.; and the time is 0.5-1h, for example, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] This invention provides an additive for reducing the crystallization point of polyester-modified MDI. It uses a first polyester polyol, a diisocyanate, and a monool compound as raw materials to obtain a plasticizer-like compound in which both hydroxyl and isocyanate groups are fully reacted, thus reducing the crystallinity of the resin molecules. Simultaneously, the molecular weight of this additive is higher than that of conventional plasticizers in the prior art, making it less prone to precipitation in the finished product and ensuring its stability. Furthermore, this additive exhibits good compatibility with other components in the subsequent modified MDI system, thereby effectively reducing its crystallinity.

[0069] This invention controls the content of each component to ensure that both hydroxyl and isocyanate groups react completely, while minimizing the amount of small molecules without polyester structure. If the amount of isocyanate is too low, excess hydroxyl groups will not react and will participate in the subsequent synthesis reaction of MDI prepolymer, affecting the performance of the product. Conversely, if the amount of isocyanate is too high, more monools are needed for end-capping, generating more small molecules without polyester structure, which increases the risk of subsequent precipitation. Detailed Implementation

[0070] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0071] Example 1

[0072] This embodiment provides an additive for reducing the crystallization point of polyester-modified MDI. The raw materials for preparing the additive include the following components in parts by weight:

[0073]

[0074] The number-average molecular weight of poly(2-methyl-1,3-propanediol adipate) diol is 2000 g / mol, and the freezing point of isophorone diisocyanate is approximately -60°C.

[0075] This embodiment also provides a method for preparing the above-mentioned additive for reducing the crystallization point of polyester-modified MDI, which includes the following steps:

[0076] (1) According to the formula, 2-methyl-1,3-propanediol adipate was dehydrated under vacuum at 110°C for 2 hours, and then cooled to about 90°C. Vacuuming was stopped, and isophorone diisocyanate was added under nitrogen gas. Stirring was continued, and the reaction was carried out at 92°C for about 1 hour. Then, dibutyltin dilaurate catalyst was added, and the reaction was continued at 92°C for 2 hours to obtain the prepolymer.

[0077] (2) Cool the prepolymer obtained in step (1) to 60°C, add 2-ethylhexanol, and control the reaction to be exothermic. Gradually raise the temperature to 92°C and continue the reaction for 3 hours. After the reaction is complete, cool down and discharge the material, seal and store it to obtain the additive used to reduce the crystallization point of polyester-modified MDI, denoted as C1.

[0078] Example 2

[0079] This embodiment provides an additive for reducing the crystallization point of polyester-modified MDI. The raw materials for preparing the additive include the following components in parts by weight:

[0080]

[0081] The number-average molecular weight of poly(3-methyl-1,5-pentanediol adipate) diol is 1000 g / mol, and the freezing point of hexamethylene diisocyanate is approximately -67°C.

[0082] This embodiment also provides a method for preparing the above-mentioned additive for reducing the crystallization point of polyester-modified MDI, which includes the following steps:

[0083] (1) According to the formula, the poly(3-methyl-1,5-pentanediol adipate) diol was dehydrated under vacuum at 110°C for 2 hours, and then cooled to about 90°C. Vacuuming was stopped, and hexamethylene diisocyanate was added under nitrogen gas. Stirring was continued, and the reaction was carried out at 92°C for about 1 hour. Then, dibutyltin dilaurate catalyst was added, and the reaction was continued at 92°C for 2 hours to obtain the prepolymer.

[0084] (2) Cool the prepolymer obtained in step (1) to 60°C, add 2-ethylhexanol, and control the reaction to be exothermic. Gradually raise the temperature to 92°C and continue the reaction for 3 hours. After the reaction is complete, cool down and discharge the material, seal and store it to obtain the additive used to reduce the crystallization point of polyester-modified MDI, denoted as C2.

[0085] Example 3

[0086] This embodiment provides an additive for reducing the crystallization point of polyester-modified MDI. The raw materials for preparing the additive include the following components in parts by weight:

[0087]

[0088] The number-average molecular weight of poly(2-methyl-1,3-propanediol adipate) diol is 2000 g / mol, and the freezing point of isophorone diisocyanate is approximately -60°C.

[0089] This embodiment also provides a method for preparing the above-mentioned additive for reducing the crystallization point of polyester-modified MDI, which includes the following steps:

[0090] (1) According to the formula, 2-methyl-1,3-propanediol adipate was dehydrated under vacuum at 110°C for 2 hours, and then cooled to about 90°C. Vacuuming was stopped, and isophorone diisocyanate was added under nitrogen gas. Stirring was continued, and the reaction was carried out at 92°C for about 1 hour. Then, dibutyltin dilaurate catalyst was added, and the reaction was continued at 92°C for 2 hours to obtain the prepolymer.

[0091] (2) Cool the prepolymer obtained in step (1) to 60°C, add n-octanol, and control the reaction to be exothermic. Gradually raise the temperature to 92°C and continue the reaction for 3 hours. After the reaction is complete, cool down and discharge the material, seal and store it to obtain the additive used to reduce the crystallization point of polyester-modified MDI, denoted as C3.

[0092] Example 4

[0093] The difference between this embodiment and Example 1 is that the poly(2-methyl-1,3-propanediol adipate) diol is replaced with poly(1,3-propanediol adipate) diol without side groups.

[0094] The raw materials for preparing the additive include the following components by weight:

[0095]

[0096] The number-average molecular weight of poly(1,3-propanediol adipate) diol is 2000 g / mol, and the freezing point of isophorone diisocyanate is about -60℃. The resulting additive is designated as C#1.

[0097] Example 5

[0098] The difference between this embodiment and Embodiment 1 is that IPDI is replaced with 4,4'-diphenylmethane diisocyanate (MDI);

[0099] The raw materials for preparing the additive include the following components by weight:

[0100]

[0101] The number-average molecular weight of poly(2-methyl-1,3-propanediol adipate) diol is 2000 g / mol, and the freezing point of 4,4'-diphenylmethane diisocyanate is approximately 38°C.

[0102] This embodiment also provides a method for preparing the above-mentioned additive for reducing the crystallization point of polyester-modified MDI, which includes the following steps:

[0103] (1) According to the formula, the poly(2-methyl-1,3-propanediol adipate) diol was dehydrated under vacuum at 110°C for 2 hours, and then cooled to about 90°C. The vacuum was stopped, and MDI was added under nitrogen gas. The mixture was stirred continuously and reacted at 80°C for about 2 hours to obtain the prepolymer.

[0104] (2) Cool the prepolymer obtained in step (1) to 60°C, add 2-ethylhexanol, and control the reaction to be exothermic. Gradually raise the temperature to 80°C and continue the reaction for 2 hours. After the reaction is complete, cool down and discharge the material. Seal and store the material to obtain the additive used to reduce the crystallization point of polyester-modified MDI, denoted as C#2.

[0105] Example 6

[0106] The difference between this embodiment and Embodiment 2 is that IPDI is replaced with 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), which has a higher freezing point.

[0107] The raw materials for preparing the additive include the following components by weight:

[0108]

[0109] The number average molecular weight of poly(3-methyl-1,5-pentanediol adipate) diol is 1000 g / mol, the freezing point of hydrogenated MDI is 10-15 °C, and all other conditions are the same as in Example 2. The resulting additive is designated as C#3.

[0110] Polyester-modified MDI was prepared using the additives provided in Examples 1-6, and the corresponding preparation examples are shown below:

[0111] Preparation Example 1

[0112] This preparation example provides a polyester-modified MDI, the raw materials for preparing the polyester-modified MDI comprising the following components in parts by weight:

[0113]

[0114] Among them, the number average molecular weight of polyester polyol HDPOL-2420 is 2000 g / mol.

[0115] This preparation example also provides a method for preparing the above-mentioned polyester-modified MDI, which includes the following steps:

[0116] (A) According to the formula, the polyester polyol HDPOL-2420 was vacuum dehydrated at 110°C for 2 hours, and then cooled to about 60°C. Vacuum dehydration was stopped, and 4,4'-diphenylmethane diisocyanate and additive C1 were added under nitrogen gas. Stirring was continued, and the reaction was carried out at 75°C for 2 hours to obtain the prepolymer.

[0117] (B) Cool the prepolymer obtained in step (A) to 60°C, add liquefied MDI and benzoyl chloride, continue stirring for 1 hour under nitrogen protection, cool down, discharge and seal for storage to obtain the polyester-modified MDI, which is measured to have NCO% = 20%.

[0118] Preparation Example 2

[0119] This preparation example provides a polyester-modified MDI, the raw materials for preparing the polyester-modified MDI comprising the following components in parts by weight:

[0120]

[0121] Among them, the number average molecular weight of polyester polyol HDPOL-2520 is 2000 g / mol.

[0122] This preparation example also provides a method for preparing the above-mentioned polyester-modified MDI, which includes the following steps:

[0123] (A) According to the formula, the polyester polyol HDPOL-2520 was vacuum dehydrated at 110°C for 2 hours, and then cooled to about 60°C. Vacuum dehydration was stopped, and 4,4'-diphenylmethane diisocyanate and additive C2 were added under nitrogen gas. Stirring was continued, and the reaction was carried out at 75°C for 2 hours to obtain the prepolymer.

[0124] (B) Cool the prepolymer obtained in step (A) to 60°C, add liquefied MDI and benzoyl chloride, continue stirring for 1 hour under nitrogen protection, cool down, discharge and seal for storage to obtain the polyester-modified MDI, which is measured to have NCO% = 22%.

[0125] Preparation Example 3

[0126] The difference between this preparation example and Preparation Example 1 is that the additive is replaced with an equal amount of C3, while all other aspects are the same as in Preparation Example 1.

[0127] Preparation Example 4

[0128] The difference between this preparation example and preparation example 1 is that the additive is replaced with an equal amount of C#1, while all other aspects are the same as preparation example 1.

[0129] Preparation Example 5

[0130] The difference between this preparation example and preparation example 1 is that the additive is replaced with an equal amount of C#2, while all other aspects are the same as preparation example 1.

[0131] Preparation Example 6

[0132] The difference between this preparation example and preparation example 2 is that the additive is replaced with an equal amount of C#3, while all other aspects are the same as preparation example 2.

[0133] Comparative Preparation Example 1

[0134] The difference between this comparative preparation example and preparation example 1 is that the additive is replaced with an equal weight amount of the plasticizer acetylthiocitrate tributyl ester (ATBC), otherwise it is the same as preparation example 1.

[0135] Comparative Preparation Example 2

[0136] The difference between this comparative preparation example and preparation example 2 is that the additive is replaced with an equal amount of propylene carbonate (PC), while all other aspects are the same as preparation example 2.

[0137] Comparative preparation example 3

[0138] This comparative preparation example provides a polyester-modified MDI. The raw materials for preparing the polyester-modified MDI include the following components in parts by weight:

[0139]

[0140]

[0141] Among them, the number average molecular weight of polyester polyol HDPOL-2420 is 2000 g / mol.

[0142] This comparative preparation example also provides a method for preparing the above-mentioned polyester-modified MDI, which includes the following steps:

[0143] (A) According to the formula, the polyester polyol HDPOL-2420 was dehydrated under vacuum at 110°C for 2 hours, and then cooled to about 60°C. The vacuuming was stopped, and diphenylmethane diisocyanate was added under nitrogen gas. Stirring was continued, and the reaction was carried out at 75°C for 2 hours to obtain the prepolymer.

[0144] (B) Cool the prepolymer obtained in step (A) to 60°C, add carbodiimide-modified diphenylmethane diisocyanate and benzoyl chloride, continue stirring for 1 hour under nitrogen protection, cool down, discharge and seal for storage to obtain the polyester-modified MDI, which is measured to have NCO% = 20%.

[0145] Comparative preparation example 4

[0146] This comparative preparation example provides a polyester-modified MDI. The raw materials for preparing the polyester-modified MDI include the following components in parts by weight:

[0147]

[0148] Among them, the number average molecular weight of polyester polyol HDPOL-2520 is 2000 g / mol.

[0149] This comparative preparation example also provides a method for preparing the above-mentioned polyester-modified MDI, which includes the following steps:

[0150] (A) According to the formula, the polyester polyol HDPOL-2520 was vacuum dehydrated at 110°C for 2 hours, and then cooled to about 60°C. Vacuum dehydration was stopped, and diphenylmethane diisocyanate was added under nitrogen gas. Stirring was continued, and the reaction was carried out at 75°C for 2 hours to obtain the prepolymer.

[0151] (B) Cool the prepolymer obtained in step (A) to 60°C, add liquefied MDI and benzoyl chloride, continue stirring for 1 hour under nitrogen protection, cool down, discharge and seal for storage to obtain the polyester-modified MDI, which is measured to have NCO% = 22%.

[0152] Test conditions

[0153] The polyester-modified MDI provided in Preparation Examples 1 to 6 and Comparative Preparation Examples 1 to 4 were tested using the following methods:

[0154] (1) Crystallization ability: The crystallization ability was evaluated by freezing test using a constant temperature refrigerator: 1000g of each sample was taken at room temperature and placed into a sealed transparent sample bottle, and placed in a constant temperature refrigerator. The sample was placed at 20℃, 15℃, 10℃, 5℃ and 0℃ for 7 days in sequence, and the crystallization of the sample was observed.

[0155] (2) Mechanical properties: The above-mentioned polyester modified MDI samples were prepared by mixing with HD-4160, component A of the shoe sole raw material from Shanghai Huide Technology Co., Ltd. (with 1.5% catalyst A33 and 0.4% water) using a polyurethane low-pressure foaming machine, and the physical properties of the samples were tested.

[0156] The test results are shown in Tables 1 and 2:

[0157] Table 1

[0158] Preparation Example 1 × △ ○ ○ ○ Preparation Example 2 × △ ○ ○ ○ Preparation Example 3 × △ ○ ○ ○ Preparation Example 4 × × △ △ ○ Preparation Example 5 × × × △ ○ Preparation Example 6 × × △ △ ○ Comparative Preparation Example 1 × △ ○ ○ ○ Comparative Preparation Example 2 × △ ○ ○ ○ Comparative preparation example 3 × × × △ ○ Comparative preparation example 4 × × × △ ○

[0159] Note: ○ indicates "clear and transparent", △ indicates "partially crystallized", and × indicates "completely crystallized".

[0160] Table 2

[0161]

[0162] As shown in Tables 1 and 2, compared to Comparative Preparation Example 3, and compared to Comparative Preparation Example 4, Preparation Example 2 showed a significant decrease in crystallization temperature from 15℃ to approximately 5℃, indicating a substantial reduction in the crystallization point. Comparative Preparation Examples 1 and 2 both incorporated traditional plasticizers, resulting in a significant decrease in crystallization point, but their tensile strength, tear strength, and abrasion resistance were all significantly reduced. In contrast, the products prepared using Preparation Examples 1 and 2 showed no significant decrease in tensile strength or tear strength, and exhibited reduced abrasion wear, indicating a partial improvement in abrasion resistance.

[0163] Preparation Example 4 used an additive prepared from a polyester polyol without side groups, while Preparation Examples 5 and 6 used an additive prepared from an isocyanate with a higher freezing point. The mechanical properties of the three products did not show a significant decrease, but the effect of reducing the crystallization point of polyester-modified MDI was not as good as that of Preparation Examples 1 and 2.

[0164] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An additive for lowering the crystallization point of polyester-modified MDI, characterized in that, The raw materials for preparing the additive include the following components in parts by weight: 100 parts of the first polyester polyol Diisocyanate 14.8~44.4 parts Monools: 8.7–26 parts Catalyst 0~0.1 parts; The first polyester polyol is obtained by copolymerizing a diol compound with side groups and adipic acid; The freezing point of the binary isocyanate is not higher than 10°C.

2. The additive according to claim 1, characterized in that, The raw materials for preparing the additive include the following components in parts by weight: 100 parts of the first polyester polyol Diisocyanate 16.8~44.4 parts 13-26 parts of monool compounds Catalyst 0~0.03 parts.

3. The additive according to claim 1, characterized in that, The functionality of the first polyester polyol is 2.

4. The additive according to claim 1, characterized in that, The side groups of the diol compounds having side groups include at least one of methyl, ethyl, butyl, or phenyl.

5. The additive according to claim 4, characterized in that, The side group of the diol compound having a side group is methyl.

6. The additive according to claim 1, characterized in that, The diols with side groups include any one or a combination of at least two of 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, or 3-methyl-1,5-pentanediol.

7. The additive according to claim 6, characterized in that, The diol compounds with side groups are 2-methyl-1,3-propanediol and / or 3-methyl-1,5-pentanediol.

8. The additive according to claim 1, characterized in that, The number average molecular weight of the first polyester polyol is 700~5000 g / mol.

9. The additive according to claim 8, characterized in that, The number average molecular weight of the first polyester polyol is 1000~2000 g / mol.

10. The additive according to claim 1, characterized in that, The freezing point of the binary isocyanate is no higher than -50°C.

11. The additive according to claim 1, characterized in that, The diisocyanate includes any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate, or toluene diisocyanate.

12. The additive according to claim 11, characterized in that, The diisocyanate is isophorone diisocyanate and / or hexamethylene diisocyanate.

13. The additive according to claim 1, characterized in that, The monools include monools with side groups.

14. The additive according to claim 13, characterized in that, The side groups of the monool compounds having side groups include alkyl groups.

15. The additive according to claim 14, characterized in that, The side group of the monool compound having a side group is ethyl.

16. The additive according to claim 13, characterized in that, The monools with side groups include any one or a combination of at least two of 2-ethylhexanol, isopropanol, or isobutanol.

17. The additive according to claim 16, characterized in that, The monool compound with side groups is 2-ethylhexanol.

18. The additive according to claim 1, characterized in that, The catalyst includes an organotin catalyst.

19. The additive according to claim 18, characterized in that, The organotin catalyst includes dibutyltin dilaurate and / or stannous octoate.

20. A method for preparing an additive for reducing the crystallization point of polyester-modified MDI according to any one of claims 1-19, characterized in that, The method includes the following steps: (1) The first polyester polyol, diisocyanate and optional catalyst are reacted according to the formula to obtain the prepolymer; (2) The prepolymer obtained in step (1) is reacted with a monool compound to obtain the additive used to reduce the crystallization point of polyester-modified MDI.

21. The method according to claim 20, characterized in that, In step (1), the first polyester polyol needs to undergo a pretreatment before the reaction.

22. The method according to claim 21, characterized in that, The pretreatment includes a dehydration process.

23. The method according to claim 22, characterized in that, The primary dehydration process is carried out under vacuum.

24. The method according to claim 22, characterized in that, The temperature of the first dehydration treatment is 100~120℃, and the time is 2~3h.

25. The method according to claim 20, characterized in that, The reaction described in step (1) is carried out under an inert atmosphere.

26. The method according to claim 20, characterized in that, The reaction in step (1) is carried out at a temperature of 90-95°C for 3-4 hours.

27. The method according to claim 20, characterized in that, The reaction in step (2) is carried out at a temperature of 90-95°C for 3-4 hours.

28. A polyester-modified MDI, characterized in that, The raw materials for preparing the polyester-modified MDI include the additives for lowering the crystallization point of the polyester-modified MDI according to any one of claims 1-19, and the raw materials for preparing the polyester-modified MDI include the following components by weight: 20-35 parts of the second polyester polyol 55-70 parts of 4,4'-diphenylmethane diisocyanate 3-10 parts of additives for lowering the crystallization point of polyester-modified MDI 5-10 parts of liquefied MDI Polymerization inhibitor 0.002~0.01 parts.

29. The polyester-modified MDI according to claim 28, characterized in that, The raw materials for preparing the polyester-modified MDI include the following components by weight: 20-30 parts of the second polyester polyol 55-65 parts of 4,4'-diphenylmethane diisocyanate 5-10 parts of additives for lowering the crystallization point of polyester-modified MDI 8-10 parts of liquefied MDI Polymerization inhibitor 0.005~0.01 parts.

30. The polyester-modified MDI according to claim 28, characterized in that, The functionality of the second polyester polyol is 2.

31. The polyester-modified MDI according to claim 28, characterized in that, The second polyester polyol is prepared by copolymerizing one or more of ethylene glycol, diethylene glycol or 1,4-butanediol with adipic acid or terephthalic acid.

32. The polyester-modified MDI according to claim 31, characterized in that, The second polyester polyol is polyethylene adipate diethylene glycol diol and / or polyethylene adipate butylene glycol diol.

33. The polyester-modified MDI according to claim 28, characterized in that, The number average molecular weight of the second polyester polyol is 1000~3000 g / mol.

34. The polyester-modified MDI according to claim 33, characterized in that, The number-average molecular weight of the second polyester polyol is 2000 g / mol.

35. The polyester-modified MDI according to claim 28, characterized in that, The liquefied MDI is carbodiimide-modified diphenylmethane diisocyanate.

36. The polyester-modified MDI according to claim 28, characterized in that, The polymerization inhibitor includes inorganic acids, organic acids, or benzoyl chloride.

37. The polyester-modified MDI according to claim 36, characterized in that, The polymerization inhibitor is benzoyl chloride.

38. A method for preparing polyester-modified MDI according to any one of claims 28-37, characterized in that, The method includes the following steps: (A) The second polyester polyol, 4,4'-diphenylmethane diisocyanate and the additive for reducing the crystallization point of polyester-modified MDI according to any one of claims 1-19 are reacted according to the formulation amount to obtain a prepolymer; (B) The prepolymer obtained in step (A), liquefied MDI and polymerization inhibitor are mixed to obtain the polyester-modified MDI.

39. The method according to claim 38, characterized in that, In step (A), the second polyester polyol needs to be pretreated before the reaction.

40. The method according to claim 39, characterized in that, The pretreatment includes dehydration.

41. The method according to claim 40, characterized in that, The dehydration process is carried out under vacuum.

42. The method according to claim 40, characterized in that, The dehydration process is carried out at a temperature of 100-120℃ for 2-3 hours.

43. The method according to claim 38, characterized in that, The reaction described in step (A) is carried out under an inert atmosphere.

44. The method according to claim 38, characterized in that, The reaction in step (A) is carried out at a temperature of 70-80°C for 2-3 hours.

45. The method according to claim 38, characterized in that, The reaction in step (B) is carried out at a temperature of 50-60°C for 0.5-1 h.

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