Polyol, preparation method thereof and application of polyol in casting polyurethane elastomer
By using pentaerythritol-grafted caprolactone polyol to introduce chemical cross-linking points in the prepolymer synthesis stage, the problem of dynamic endogenous heat generation in polyurethane elastomers was solved, and the dynamic performance was improved and the service life was extended.
Patent Information
- Application Number
- CN202511015538.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2025-09-09
AI Technical Summary
Existing polyurethane elastomers have insufficient performance in terms of dynamic endogenous heat generation, which causes the material to soften at excessively high temperatures and shorten its service life. Existing improvement methods are costly or affect mechanical properties.
Pentaerythritol-grafted caprolactone polyols are used to replace traditional small molecule polyols. Chemical cross-linking points are introduced in the prepolymer synthesis stage through the semi-prepolymer method to increase the network structure and improve the tightness and dynamic performance of the molecular chain links.
Without affecting the mechanical properties, it significantly improves the dynamic properties of polyurethane elastomers, reduces internal heat and extends service life.
Smart Images
Figure CN120607695A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of polyurethane, in particular to a polyol and a preparation method thereof and application thereof in a cast polyurethane elastomer. Background Art
[0002] Polyurethane elastomers include cast polyurethane elastomers (CPUs), thermoplastic polyurethane elastomers (TPUs), and millable polyurethane elastomers (MPUs). CPUs are produced through a casting process followed by reaction molding and are sometimes referred to as "casting rubber." CPUs have the highest production volume and are currently the most predominant type of polyurethane elastomer. CPUs are a new polymer material between rubber and plastic, often used as an alternative to rubber products in practical applications. CPUs possess excellent wear resistance, the best among elastomers. They are liquid at room temperature and solidify after processing, making them commonly used in casting processes such as casters, mining, oil refining, textiles, and printing rollers. The finished products are exceptionally wear-resistant.
[0003] Dynamic endogenous heat is a very important performance parameter for products such as seals, casters, and rubber rollers in hydraulic systems. Dynamic endogenous heat refers to the heat generated by molecular chain friction and hysteresis effects in elastomeric products under alternating stress. The soft segment (such as polyether or polyester polyol) and hard segment (isocyanate and chain extender) of the CPU undergo relative displacement during dynamic deformation. The friction and hysteresis effects between the molecular chains convert mechanical energy into thermal energy. If the heat cannot be dissipated in time, the material temperature will be too high and soften, or even age, which will significantly reduce its service life. Currently, the main methods for improving the dynamic properties of products are to use high-rigidity, high-symmetry isocyanates (such as NDI, PPDI, CHDI) to enhance the crystallinity of the hard segment, improve the degree of microphase separation, reduce the internal friction of the soft segment chain movement, and add carbon fiber, graphene or aluminum nitride to improve its thermal conductivity, accelerate heat diffusion, and avoid local temperature rise. However, the former is relatively expensive, making the elastomer products more expensive. At the same time, it has high reaction activity, poor process performance, and is difficult to operate manually. The latter, due to the addition of external additives, will reduce the mechanical strength and flexibility of the elastomer material. Summary of the Invention
[0004] Based on the above background and status, in order to solve the above technical problems, the present invention proposes a polyol and a preparation method thereof and an application in a cast polyurethane elastomer. The cast polyurethane elastomer prepared using the polyol has significantly improved dynamic properties while maintaining little change in mechanical properties.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A polyol having the following general structural formula:
[0006] Wherein, the number average weight of the polyol is 3733-4426.
[0007] A method for preparing a polyol, comprising the following steps: Pentaerythritol, caprolactone and a catalyst are added to a reaction vessel, the temperature is raised to 50-60° C., the vacuum is controlled at 0.1 KPa for dehydration, the vacuum is stopped when the moisture content is below 200 ppm, and the vacuum is broken with dry nitrogen to obtain a mixture; under the protection of dry nitrogen, the mixture is heated to 150-160° C. for reaction, and after reacting for 4-5 hours, the reaction vessel is vacuumed to maintain the pressure at 0.1 KPa for 1±0.5 hours to remove unreacted monomers, and the temperature is lowered and the material is discharged to obtain the polyol; the number average molecular weight of the polyol is 3733-4426, and the hydroxyl value is 50.86 mg KOH / g-60.72 mg KOH / g.
[0008] In a further improvement, the mass ratio of the pentaerythritol, caprolactone and catalyst is 9.27-11.03:288.97-290.73:0.03.
[0009] As a further improvement, the catalyst is an organotin or organotitanium catalyst.
[0010] In a further improvement, the organic tin catalyst includes one or more of stannous octoate, dibutyltin oxide, dibutyltin dilaurate and tetraphenyltin; and the organic titanium catalyst includes one or more of tetrabutyl titanate and tetrapropyl titanate.
[0011] The invention discloses an application of a polyol in a cast polyurethane elastomer. The polyol is as described above and is used as a raw material for preparing the cast polyurethane elastomer.
[0012] Further improvements include the following steps: S1. The polyol and oligomer diol are mixed in a reaction vessel, and then the temperature is raised to 110-120° C., and the pressure in the reaction vessel is maintained at 0.1 KPa under vacuum for 1-2 hours to remove water to obtain a dehydrated mixed polyol. The dehydrated mixed polyol is added to diphenylmethane diisocyanate preheated to 50-60° C., and the system temperature is controlled at 70-80° C. to react for 2-3 hours to obtain prepolymer A. S2. Take prepolymer A, add 1,4-butanediol according to the chain extension coefficient of 0.95, stir quickly and degas, then pour into a mold preheated at 120°C, vulcanize for 1 hour, demould, and continue to vulcanize at 110°C for 24 hours to obtain a cast polyurethane elastomer.
[0013] As a further improvement, the oligomer diol is polycaprolactone diol with a number average molecular weight of 2000.
[0014] In a further improvement, the mass ratio of the polyol to the oligomer diol is 12-24:156-168.
[0015] According to a further improvement, the mass ratio of the dehydrated mixed polyol to diphenylmethane diisocyanate is 150:75.
[0016] The beneficial effects of the present invention are: The present invention uses pentaerythritol grafted caprolactone to replace traditional small molecule polyols for chain extension. The present invention uses a semi-prepolymer method to produce a cast polyurethane elastomer. The difference is that in the prepolymer synthesis stage, a part of the pentaerythritol grafted caprolactone polyol is used to replace a part of the polyether or polyester diol to produce the prepolymer, so that a part of chemical crosslinking points are introduced into the material system in the prepolymer synthesis stage. On the one hand, a part of the network structure is added to make the links between the molecular chains tighter, so that the mechanical properties of the polyurethane elastomer are improved. On the other hand, because the molecular chains of the crosslinking points are long enough, the microphase separation degree of the soft and hard segments will not be reduced like a small molecule crosslinking agent, so the dynamic properties of the elastomer are improved, the endogenous heat is reduced, and the service life of the polyurethane elastomer is extended. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is the molecular weight detection diagram of Example 1. DETAILED DESCRIPTION
[0018] The present invention will be further described below with reference to specific examples, but the present invention is not limited to the following examples. Unless otherwise specified, the raw materials used in the examples and comparative examples are commercially available and can be purchased through commercial channels.
[0019] The water content was tested using a trace moisture meter; the hydroxyl value was tested according to GB / T 12008.3-2009 Method A; and the number average molecular weight (Mn) was tested using Shimadzu gel permeation chromatography (GPC). Example 1
[0020] 10.2g of pentaerythritol, 289.8g of caprolactone, and 0.03g of stannous octoate were added to a four-necked flask. The temperature was raised to 55°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 1.5 hours. A microinjection needle was used to sample the material and the water content was 164 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 155°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1.5 hours to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 56.25 mg KOH / g and the Mn was 3990.
[0021] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 2.5 hours. The NCO content was tested to be 8.36%. 17.04 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested. Example 2
[0022] 11.03g of pentaerythritol, 288.97g of caprolactone, and 0.03g of dibutyltin dilaurate were added to a four-necked flask. The temperature was raised to 60°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 1 hour. A microinjection needle was used to sample the material and the water content was 171ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 160°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 60.72mg KOH / g and the Mn was 3733.
[0023] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 2.5 hours. The NCO content was tested to be 8.34%. 16.98 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested. Example 3
[0024] 9.27g of pentaerythritol, 290.73g of caprolactone, and 0.03g of stannous octoate were added to a four-necked flask. The temperature was raised to 50°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 2 hours. A microinjection needle was used to sample the material and the water content was 169 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 160°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 50.86 mg KOH / g and the Mn was 4426.
[0025] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 2.5 hours. The NCO content was tested to be 8.4%. 17.15 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested. Example 4
[0026] 10.2g of pentaerythritol, 289.8g of caprolactone, and 0.03g of tetrabutyl titanate were added to a four-necked flask. The temperature was raised to 55°C and vacuum was applied. The pressure in the flask was maintained below 0.1kPa for approximately 2 hours. A microinjection needle was used to sample the material and the water content was 141ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 155°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 56.23mg KOH / g and the Mn was 3987.
[0027] 24 g of the above polyol and 156 g of polycaprolactone diol were dehydrated in a flask at 120°C under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75°C for reaction for 2.5 hours. The NCO content was tested to be 8.36%. 17.1 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120°C oven, vulcanized at 120°C for 1 hour, demolded, and then post-vulcanized in a 110°C oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested. Example 5
[0028] 10.2g of pentaerythritol, 289.8g of caprolactone, and 0.03g of dibutyltin dilaurate were added to a four-necked flask. The temperature was raised to 60°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 2 hours. A microinjection needle was used to sample the material and the water content was 128 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 150°C under nitrogen protection. After maintaining the temperature for 5 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 56.3mg KOH / g and the Mn was 3982.
[0029] 12 g of the above polyol and 168 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 70° C. for reaction for 3 hours. The NCO content was tested to be 8.34%. 16.99 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested.
[0030] Comparative Example 1 180 g of polycaprolactone diol was dehydrated in a flask at 120°C under vacuum at 0.1 kPa for 1 hour. 150 g of the polyol and 75 g of MDI were then added to a four-necked flask and kept at 75°C for 2.5 hours. The NCO content was tested to be 8.33%. 16.96 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120°C oven, vulcanized at 120°C for 1 hour, demolded, and post-vulcanized in a 110°C oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its properties could be tested.
[0031] Comparative Example 2 20.4g of pentaerythritol, 279.6g of caprolactone, and 0.03g of stannous octoate were added to a four-necked flask. The temperature was raised to 55°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 2 hours. A microinjection needle was used to sample the material and the water content was 153 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 160°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 112.8mg KOH / g and the Mn was 1996.
[0032] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 2.5 hours. The NCO content was tested to be 8.06%. 16.42 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its properties could be tested.
[0033] Comparative Example 3 20.4g of pentaerythritol, 279.6g of caprolactone, and 0.03g of dibutyltin dilaurate were added to a four-necked flask. The temperature was raised to 60°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 1.5 hours. A microinjection needle was used to sample the material and the water content was 119 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 155°C under nitrogen protection. After maintaining the temperature for 4.5 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 111.57 mg KOH / g and the Mn was 2010.
[0034] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 77.5 g of MDI were then placed in a four-necked flask and kept at 70° C. for reaction for 3 hours. The NCO content was tested to be 8.34%. 16.99 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested.
[0035] Comparative Example 4 6.8g of pentaerythritol, 293.2g of caprolactone, and 0.03g of stannous octoate were added to a four-necked flask. The temperature was raised to 60°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 1.5 hours. A microinjection needle was used to sample the material and the water content was 130 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 160°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1 hour to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 37.51 mg KOH / g and the Mn was 6010.
[0036] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 2.5 hours. The NCO content was tested to be 8.42%. 17.15 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested.
[0037] Comparative Example 5 10.2g of pentaerythritol, 289.8g of caprolactone, and 0.03g of stannous octoate were added to a four-necked flask. The temperature was raised to 55°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 2 hours. A microinjection needle was used to sample the material and the water content was 117 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 155°C under nitrogen protection. After maintaining the temperature for 4 hours, vacuum was applied for 1.5 hours to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 56.14 mg KOH / g and the Mn was 3994.
[0038] 6 g of the above polyol and 174 g of polycaprolactone diol were dehydrated in a flask at 120°C under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75°C for reaction for 2.5 hours. The NCO content was tested to be 8.32%. 16.95 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120°C oven, vulcanized at 120°C for 1 hour, demolded, and then post-vulcanized in a 110°C oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested.
[0039] Comparative Example 6 10.2g of pentaerythritol, 289.8g of caprolactone, and 0.03g of dibutyltin dilaurate were added to a four-necked flask. The temperature was raised to 55°C and vacuum was applied. The pressure in the flask was maintained below 0.1 kPa for approximately 1.5 hours. A microinjection needle was used to sample the material and the water content was 164 ppm. The vacuum was extinguished with dry nitrogen and the temperature was raised to 155°C under nitrogen protection. After maintaining the temperature for 4.5 hours, vacuum was applied for 1.5 hours to remove unreacted monomers. The material was cooled and discharged to obtain a polyol for cast polyurethane elastomers. The hydroxyl value was 55.92 mg KOH / g and the Mn was 4014.
[0040] 18 g of the above polyol and 162 g of polycaprolactone diol were dehydrated in a flask at 120° C. under vacuum at 0.1 kPa for 1 hour to obtain a dehydrated mixed polyol. 150 g of the mixed polyol and 75 g of MDI were then placed in a four-necked flask and kept at 75° C. for reaction for 3 hours. The NCO content was tested to be 8.33%. 16.97 g of BDO was then added, and the mixture was rapidly stirred for 1 minute and degassed until no large bubbles were generated. The mixture was then poured into a mold preheated in a 120° C. oven, vulcanized at 120° C. for 1 hour, demolded, and then post-vulcanized in a 110° C. oven for 24 hours to obtain a polyurethane elastomer. The elastomer was conditioned under standard conditions for 7 days before its performance was tested.
[0041] The polyurethane elastomers obtained from the polyester polyols prepared in the examples and comparative examples were tested for hardness (Shore A) according to GB / T 531.1-2008; tensile strength and elongation at break according to GB / T 528-2009; right-angle tear strength according to GB / T 529-2008; abrasion resistance according to GB / T 1681-20098; and resilience according to GB / T 1681-2009. Dynamic properties (maximum temperature, initial height, and final height) were all tested according to GB / T 1687.3-2016 (tested at room temperature, with a frequency of 30 Hz, a stroke of 4.45 mm, a prestress of 1 MPa, and a test duration of 1 hour). The test results are as follows:
[0042] In Examples 1-5, polyester polyols of different molecular weights were obtained by grafting pentaerythritol with caprolactone. Within the appropriate molecular weight range, adding a portion of the polyester polyol to a conventional MDI-type cast polyurethane elastomer formula (Comparative Example 1) significantly improved the compression and flexural properties of the elastomer without significantly changing the mechanical properties. The viscosity of the polyol was low and the operability was good.
[0043] Comparative Example 1, a conventional cast polyurethane elastomer, exhibits poor compression-flex performance, as evidenced by a high maximum temperature. This indicates that the elastomer exhibits hysteresis under alternating stress, generating internal heat that increases the elastomer temperature. Furthermore, the final height of the specimen after testing is low, and the compression set is also poor.
[0044] Comparative Examples 2 and 3 also use pentaerythritol grafted caprolactone, but the amount of grafted caprolactone is small, the molecular weight of the polyester polyol is low, and the cross-linking chain is short, which affects the degree of microphase separation of the elastomer, causing the mechanical properties of the elastomer to decline, and the dynamic performance is also poor, and the service life of the elastomer is not long.
[0045] Comparative Example 4 uses pentaerythritol grafted with caprolactone, but the amount of grafted caprolactone is large, the molecular weight is large, and the viscosity of the polyester is very high. During the stirring and degassing process, the chain extender and the prepolymer are unevenly dispersed, and it is not easy to separate the polyurethane microphase during the vulcanization and post-adjustment of the product, resulting in relatively poor mechanical and dynamic properties of the polyurethane elastomer.
[0046] In Comparative Example 5, a small amount of polyester polyol containing pentaerythritol grafted with caprolactone is added to the conventional elastomer formula, but the improvement effect on the dynamic properties is not obvious and has no practical effect.
[0047] In Comparative Example 6, a large amount of polyester polyol grafted with pentaerythritol and caprolactone was added to the conventional elastomer formula. It was found that the mechanical properties were seriously reduced and the dynamic properties were not improved. This was because too many cross-linking points were introduced into the formula, which hindered the movement of the elastomer molecular chain.
[0048] In summary, the polyester polyol prepared based on the present invention has a simple production process and is easy to operate when preparing the elastomer. At the same time, the polyurethane elastomer prepared based on the polyol of the present invention has good mechanical properties and significantly improved dynamic properties, which can extend the service life of the polyurethane elastomer.
[0049] The above is a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and concepts of the present invention, should be covered by the scope of protection of the claims of the present invention.
Claims
1. A polyol, characterized in that The general structural formula of the polyol is as follows: ； Wherein, the number average weight of the polyol is 3733-4426.
2. A method for preparing a polyol, characterized in that: The steps include: Pentaerythritol, caprolactone and a catalyst are added to a reaction vessel, the temperature is raised to 50-60° C., the vacuum is controlled at 0.1 KPa for dehydration, the vacuum is stopped when the moisture content is below 200 ppm, and the vacuum is broken with dry nitrogen to obtain a mixture; under the protection of dry nitrogen, the mixture is heated to 150-160° C. for reaction, and after reacting for 4-5 hours, the reaction vessel is vacuumed to maintain the pressure at 0.1 KPa for 1±0.5 hours to remove unreacted monomers, and the temperature is lowered and the material is discharged to obtain the polyol; the number average molecular weight of the polyol is 3733-4426, and the hydroxyl value is 50.86 mg KOH / g-60.72 mg KOH / g.
3. The method for preparing a polyol according to claim 2, wherein: The mass ratio of pentaerythritol, caprolactone and catalyst is 9.27-11.03:288.97-290.73:0.
03.
4. The method for preparing a polyol according to claim 2, wherein: The catalyst is an organotin catalyst or an organotitanium catalyst.
5. The method for preparing a polyol according to claim 4, wherein: The organic tin catalyst includes one or more of stannous octoate, dibutyltin oxide, dibutyltin dilaurate and tetraphenyltin; the organic titanium catalyst includes one or more of tetrabutyl titanate and tetrapropyl titanate.
6. Use of a polyol in a cast polyurethane elastomer, characterized in that: The polyol is as described in any one of claims 1 to 5, and is used as a raw material for preparing a cast polyurethane elastomer.
7. Use of the polyol according to claim 6 in a cast polyurethane elastomer, characterized in that: The steps include: S1. The polyol and oligomer diol are mixed in a reaction vessel, and then the temperature is raised to 110-120° C., and the pressure in the reaction vessel is maintained at 0.1 KPa under vacuum for 1-2 hours to remove water to obtain a dehydrated mixed polyol. The dehydrated mixed polyol is added to diphenylmethane diisocyanate preheated to 50-60° C., and the system temperature is controlled at 70-80° C. to react for 2-3 hours to obtain prepolymer A. S2. Take prepolymer A, add 1,4-butanediol according to the chain extension coefficient of 0.95, stir quickly and degas, then pour into a mold preheated at 120°C, vulcanize for 1 hour, demould, and continue to vulcanize at 110°C for 24 hours to obtain a cast polyurethane elastomer.
8. Use of the polyol according to claim 7 in a cast polyurethane elastomer, characterized in that: The oligomer diol is polycaprolactone diol with a number average molecular weight of 2000.
9. Use of the polyol according to claim 7 in a cast polyurethane elastomer, characterized in that: The mass ratio of polyol to oligomer diol is 12-24:156-168.
10. Use of the polyol according to claim 7 in a cast polyurethane elastomer, characterized in that: The mass ratio of the dehydrated mixed polyol to diphenylmethane diisocyanate is 150:75.