CN112538149B

CN112538149B - Preparation process of casting polyurethane elastomer

Info

Publication number: CN112538149B
Application number: CN201910898640.1A
Authority: CN
Inventors: 刘子厚; 刘赵兴; 丁宗雷; 滕向
Original assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Priority date: 2019-09-23
Filing date: 2019-09-23
Publication date: 2022-07-12
Anticipated expiration: 2039-09-23
Also published as: CN112538149A

Abstract

The invention provides a preparation process of a casting polyurethane elastomer, which comprises the following steps: 1) reacting isocyanate with polyether polyol or polyester polyol in the presence of a tertiary amine catalyst, and adding an organic metal catalyst and a defoaming agent to prepare an elastomer material A; 2) isocyanate or a prepolymer of the isocyanate is used as an elastomer B material; 3) mixing the elastomer A, B material according to the mass ratio of 1: 1-3: 1. According to the invention, through simple prepolymer conversion, the moisture in the polyol is firstly reacted, and then the OH-terminated prepolymer in the elastomer A material, unreacted polyether polyol or polyester polyol and isocyanate or isocyanate prepolymer are reacted to generate the polyurethane elastomer, so that the preparation method has the advantages of simple process and avoidance of generation of chemical bubbles, and can solve the problem that the polyurethane elastomer has bubbles due to high moisture content caused by non-strict storage of the polyol.

Description

Preparation process of casting polyurethane elastomer

Technical Field

The invention relates to a preparation process of a polyurethane elastomer, in particular to a preparation process of a high-hardness casting polyurethane elastomer, and belongs to the technical field of polyurethane materials.

Background

Polyurethane elastomers (PUE) are a class of polymer synthetic materials with excellent overall performance, including cast polyurethane elastomers (CPU), thermoplastic polyurethane elastomers (TPU), and compounded polyurethane elastomers (MPU). The CPU is viscous liquid before processing and molding, liquid oligomer polyol, isocyanate and a micromolecular chain extender are used as raw materials, a processing and molding method of liquid mixing pouring is used, and a cured and crosslinked high-elasticity product is obtained through chain extension crosslinking reaction. The CPU molding process is simple, the formed elastomer has high molecular integrity, the characteristics of the polyurethane elastomer are exerted to the maximum extent, and the comprehensive performance is superior to MPU and TPU, so that the polyurethane elastomer is a variety with the maximum yield and the widest application range.

In order to improve the hardness, mechanical properties, optical stability and the like of the cast polyurethane elastomer, a great deal of research on the types and molecular weights of raw materials is carried out, such as the technical schemes disclosed in patent publications CN105037676A, CN105061719A and US5047494 (A). However, because the polyol component is easy to absorb water, isocyanate is very easy to react with trace moisture in the polyol to generate polyurea and carbon dioxide when being added into a reaction system, so that the internal foaming of the casting polyurethane material influences the overall appearance and the tear resistance of a product, particularly the influence on a transparent polyurethane elastomer is more obvious, bubbles with the diameter larger than 1 mu m can be generated, and the quality of the product is directly influenced. Therefore, the water requirement of the casting polyurethane in the molding process is extremely strict. Even the invention patent with patent publication No. CN104892882A requires that the water content of polyether is less than or equal to 0.003 percent, and the water content is very high.

However, the prior art has not studied much on how to avoid the problem of bubbles in the polyurethane elastomer during the molding process. Among them, the literature "bubble problem in the production of cast polyurethane elastomer articles" (Qinzenshi Swallow et al, polyurethane industry, 1995(2):36-38) teaches that the main methods for reducing chemical bubbles are: the polyether component is dehydrated under vacuum or a suitable catalyst is selected and used in larger amounts to accelerate the gelling before use. The vacuum dehydration scheme takes longer time, and the dehydration effect cannot be ensured; according to the catalyst scheme, curing molding is realized before bubbles are generated at the cost of shortening the operation time, but a downstream customer needs longer operation time and longer curing time in the construction process, so that on one hand, one-time material mixing and multiple-time construction can be realized, the efficiency is improved, and on the other hand, the longer curing time can enable the material to fully release internal stress in the molding process so as to improve the mechanical property of the material. Therefore, in view of the problem of chemical bubbles that cannot be effectively solved by the current technical means, the present patent aims to provide a process for preparing a casting type polyurethane elastomer that can remove chemical bubbles and has low requirements on water content in a polyol component.

Disclosure of Invention

The invention aims to provide a preparation process of a pouring type polyurethane elastomer, in the process of preparing an OH end-capping prepolymer, moisture in polyol reacts with isocyanate under the action of a tertiary amine catalyst to generate carbon dioxide gas and is discharged, so that bubbles are not easy to generate in the process of further preparing the elastomer without pressurization, and the mechanical property is greatly improved after curing, therefore, the invention can carry out production without strictly controlling moisture in the polyol, and has the advantages of simple operation and no bubbles.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

a preparation process of a casting polyurethane elastomer comprises the following steps:

1) reacting isocyanate with polyether polyol or polyester polyol in the presence of a tertiary amine catalyst, and adding an organic metal catalyst and a defoaming agent to prepare an elastomer material A; the adding amount of the isocyanate is 5-20 wt%, preferably 5-10 wt% of the polyether polyol or the polyester polyol in terms of mass ratio;

the addition amount of the isocyanate in the step is small, and the main purpose is to react with water in the polyol preferentially under the action of the tertiary amine catalyst to generate carbon dioxide to be discharged, so that the problem of bubbles in the elastomer is solved;

2) isocyanate or a prepolymer of the isocyanate is used as an elastomer B material;

3) mixing the A, B elastomer materials according to the mass ratio of 1: 1-3: 1, removing mechanical bubbles in vacuum, and carrying out sealing reaction to obtain the polyurethane elastomer.

Further, the polyurethane elastomer is placed into a 60-120 ℃ oven for curing after being prepared, and the operation time is 1-5 hours.

Further, the elastomer A material and the elastomer B material are subjected to vacuum defoaming after the preparation is finished, and are sealed for later use.

Further, the water content in the polyether polyol or polyester polyol is 3000ppm or less (ppm is parts per million by mass).

Furthermore, in the preparation process of the elastomer material A, isocyanate preferentially reacts with water in polyether polyol or polyester polyol under the action of a tertiary amine catalyst, and the water content participating in the reaction is 51-73 wt% of the total water content in the polyol.

According to the invention, through simple prepolymer conversion, in the first step of reaction, moisture in the polyol is firstly reacted, then the isocyanate and the polyol are reacted to generate the OH-terminated prepolymer, and in the second step of reaction, the unreacted polyether polyol or polyester polyol, the OH-terminated prepolymer and the isocyanate or the prepolymer of the isocyanate are reacted to generate the polyurethane elastomer, so that the polyurethane elastomer has the following two advantages:

on the first hand, most of water is removed through isocyanate reaction, so that chemical bubbles generated by excessive water content in polyol during elastomer preparation are avoided;

in a second aspect, the first step of the reaction also involves the formation of an OH-terminated prepolymer from isocyanate and polyol, which effectively shortens the reaction time during the preparation of the elastomer, and avoids the formation of small bubbles from the reaction of residual minor amounts of water with isocyanate and the further agglomeration of the small bubbles into larger visible bubbles.

Therefore, the method has the advantages of simple process and capability of avoiding generation of chemical bubbles during preparation of the polyurethane elastomer, and can solve the problem of bubbles of the polyurethane elastomer caused by overhigh moisture content due to non-strict storage of the polyol.

Further, the polyether polyol or polyester polyol is one or more of polyester type or polyether type transparent polyol with the functionality of 2-5 and the molecular weight range of 300-1000, preferably one or more of polyester type or polyether type transparent polyol with the molecular weight range of 300-700, and further preferably one or more of polyether polyol R2303, R2304, R2403 and R2307.

Further, the isocyanate is one or more of aliphatic or cycloaliphatic polyisocyanates, preferably one or more of ADI type isocyanates, and further preferably one or more of hexamethylene 1, 6-diisocyanate (HDI) and biuret, trimer (HT600) thereof, isophorone diisocyanate (IPDI), 1, 4-cyclohexane diisocyanate (CHDI) and 4, 4-dicyclohexylmethane diisocyanate (HMDI).

Further, the amount of the tertiary amine catalyst is 0.01-0.03 wt%, preferably 0.01-0.02 wt% of the polyether polyol or the polyester polyol in terms of mass ratio; the tertiary amine catalyst is selected from one or more of pentamethyl diethylenetriamine (PC5) and bis (dimethylaminoethyl) ether (BDMAEE), and is preferably pentamethyl diethylenetriamine.

Further, the amount of the organic metal catalyst is 0.08 to 0.15 wt%, preferably 0.10 to 0.15 wt% of the polyether polyol or the polyester polyol in terms of mass ratio; the organic metal catalyst is selected from one or more of organic bismuth catalysts or organic tin catalysts, and dibutyltin dilaurate or stannous octoate or bismuth neodecanoate is preferred.

Further, the amount of the defoaming agent is 0.1-0.2 wt%, preferably 0.1-0.15 wt% of the polyether polyol or the polyester polyol in terms of mass ratio; the defoaming agent is an organic silicon defoaming agent, preferably Guangdong Jungbang B-0599.

The technical advantages and corresponding beneficial effects of the invention are as follows:

1) the method adopts a simple prepolymer conversion method, and adds the tertiary amine catalyst to catalyze the reaction of isocyanate and water, thereby solving the problem that chemical bubbles in the elastomer are difficult to remove due to overhigh water content in polyether polyol or polyester polyol;

2) the polyurethane elastomer is prepared in a prepolymerization mode, so that the reaction process of elastomer preparation can be shortened, the formation of bubbles is further prevented, the curing time is long, and the requirement of downstream customers on the operation time can be met;

3) the polyurethane elastomer prepared by the method also has the advantages of high mechanical strength, good light transmission and wide hardness adjustment range, and can meet the use requirement of the transparent polyurethane elastomer;

4) in addition, the method has the advantages of simple operation, room-temperature curing and forming, no need of pressurization, low requirement on equipment and the like, and is suitable for large-scale production and application.

Drawings

FIG. 1 is an external view of a transparent polyurethane elastomer prepared in example 9.

FIG. 2 is an external view of a transparent polyurethane elastomer prepared in example 10.

FIG. 3 is an external view of a transparent polyurethane elastomer prepared in example 11.

FIG. 4 is an external view of a transparent polyurethane elastomer prepared in example 12.

FIG. 5 is an external view of a transparent polyurethane elastomer prepared in example 13.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not to be construed as limiting the scope of the invention.

[ example 1 ]

1) weighing polyether polyol R2307100 g, adding 10g IPDI, adding 0.03g PC5, mixing uniformly and reacting at room temperature for 24 h. Then 0.1g of dibutyltin dilaurate and 0.1g of defoamer are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and stored in a sealed manner for standby.

2) And (3) respectively weighing IPDI and HT600 in equal parts by mass, uniformly mixing, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, obtaining an elastomer B material, and sealing and storing for later use.

3) Mixing the elastomer A, B material according to the weight ratio of 2.3: 1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

[ example 2 ]

1) Weighing polyether polyol R2310100 g, adding 5g of IPDI, adding 0.02g of BDMAEE, mixing uniformly and reacting at room temperature for 24 h. Then 0.15g of stannous octoate and 0.2g of defoamer are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, the elastomer A material is prepared, and the elastomer A material is sealed and stored for later use.

2) According to HMDI: and weighing the materials according to the mass ratio of HT600 to 9:2, uniformly mixing, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, obtaining an elastomer B material, and sealing and storing for later use.

3) Mixing the elastomer A, B material according to the weight ratio of 3:1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into a 60 ℃ oven and curing for 5 hours to obtain the transparent polyurethane elastomer.

[ example 3 ]

1) Polyether polyols R230373 g and R240327 g were weighed out and mixed uniformly, 7g HDI was added thereto, 0.02g PC5 was added and mixed uniformly for reaction at room temperature for 24 hours. Then 0.08g of dibutyltin dilaurate and 0.15g of defoaming agent are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and is sealed and stored for later use.

2) According to IPDI: and weighing the materials according to the mass ratio of HT600 to 9:1, uniformly mixing the materials, defoaming the mixture in vacuum, and enabling the vacuum degree to be not less than-0.095 MPa to obtain an elastomer B material, and sealing and storing the elastomer B material for later use.

3) Mixing the elastomer A, B material according to the ratio of 1:1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into a 120 ℃ oven and curing for 1h to obtain the transparent polyurethane elastomer.

[ example 4 ] A method for producing a polycarbonate

1) Polyether polyol R2303100 g was weighed, 20g IPDI was added thereto, and 0.01g PC5 was added thereto, mixed uniformly and reacted at room temperature for 24 hours. Then 0.1g of dibutyltin dilaurate and 0.16g of defoaming agent are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and is sealed and stored for later use.

2) And (3) carrying out vacuum defoaming on the IPDI with the vacuum degree being not less than-0.095 MPa to obtain an elastomer B material, and sealing and storing for later use.

3) Mixing an elastomer A, B material according to the weight ratio of 1.3: 1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

[ example 5 ]

1) Polyether polyols R230450 g and R231050 g are weighed respectively and mixed uniformly, 15g of HMDI is added into the mixture, 0.01g of PC5 is added into the mixture and mixed uniformly to react for 24 hours at room temperature. Then 0.12g of bismuth neodecanoate and 0.12g of defoamer are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and stored in a sealed manner for standby.

2) According to IPDI: and weighing the materials according to the mass ratio of HT600 to 3:1, uniformly mixing the materials, defoaming the mixture in vacuum, and enabling the vacuum degree to be not less than-0.095 MPa to obtain an elastomer B material, and sealing and storing the elastomer B material for later use.

3) Mixing the elastomer A, B material according to the ratio of 3:1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a mold for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

[ example 6 ]

1) Polyether polyols R240375 g and R231025 g were weighed respectively, 8g IPDI was added thereto, and 0.026g PC5 was added thereto, and the mixture was mixed uniformly and reacted at room temperature for 24 hours. Then 0.11g of bismuth neodecanoate and 0.15g of defoamer are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and stored in a sealed manner for standby.

2) Weighing 100g of IPDI, adding 17g of polyether polyol R2303, reacting at 80 ℃ for 6 hours, cooling to room temperature, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, so as to obtain an elastomer B material with the isocyanate content of the prepolymer of 25.5-26.5%, and sealing and storing for later use.

3) Mixing the elastomer A, B material according to the weight ratio of 1:1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

[ example 7 ]

1) Weighing polyether polyol R2304100 g, adding 14g IPDI, adding 0.022g BDMAEE, mixing uniformly and reacting at room temperature for 24 h. And then adding 0.13g of stannous octoate and 0.13g of defoaming agent, uniformly mixing, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, preparing the elastomer A material, and sealing and storing for later use.

2) Weighing 100g of HMDI, adding 10g of polyether polyol R2304, reacting at 85 ℃ for 5 hours, cooling to room temperature, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, so as to obtain an elastomer B material with the isocyanate content of the prepolymer of 28.5-29.5%, and sealing and storing for later use.

3) Mixing the elastomer A, B material according to the weight ratio of 1.26: 1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

[ example 8 ]

1) Polyether polyols R230380 g and R230720 g were weighed out, 9g of HDI were added thereto, and 0.015g of PC5 were added thereto and mixed well for reaction at room temperature for 24 hours. Then 0.09g of dibutyltin dilaurate and 0.09g of defoaming agent are added, the mixture is uniformly mixed and defoamed in vacuum, the vacuum degree is not less than-0.095 MPa, and the elastomer A material is prepared and is sealed and stored for later use.

2) Weighing 100g of IPDI, adding 30g of polyether polyol R2307, reacting at 80 ℃ for 6 hours, cooling to room temperature, defoaming in vacuum, wherein the vacuum degree is not less than-0.095 MPa, obtaining the elastomer B material with the isocyanate content of the prepolymer of 24.5-25.5%, and sealing and storing for later use.

[ example 9 ]

A clear polyurethane elastomer was prepared by blending a polyether polyol R2307 having a water content of 3000. + -.50 ppm and following the procedures and parameters of example 1, the appearance of the elastomer is shown in FIG. 1.

[ example 10 ]

A clear polyurethane elastomer was prepared by blending a polyether polyol R2307 having a water content of 2500. + -.50 ppm according to the process and parameters described in example 1, the elastomer appearance being shown in FIG. 2.

[ example 11 ]

A clear polyurethane elastomer was prepared by blending a polyether polyol R2307 having a water content of 2000. + -.50 ppm and following the procedure and parameters of example 1, the appearance of the elastomer is shown in FIG. 3.

[ example 12 ]

Polyether polyol R2307 with water content of 1500 + -50 ppm is prepared, and transparent polyurethane elastomer is prepared according to the process and parameters in example 1, and the appearance of the elastomer is shown in FIG. 4.

[ example 13 ]

A clear polyurethane elastomer was prepared by blending a polyether polyol R2307 having a water content of 1000. + -.50 ppm and following the procedures and parameters of example 1, the appearance of the elastomer is shown in FIG. 5.

Comparative example 1

1) And (3) blending and weighing polyether polyol R2303100 g with the water content of 0.2%, adding 0.3g of dibutyltin dilaurate and 0.1g of defoaming agent, uniformly mixing, and defoaming in vacuum with the vacuum degree being not less than-0.095 MPa to prepare an elastomer A material, and sealing and storing for later use.

2) Respectively weighing equal parts by mass of IPDI and HT600, uniformly mixing, defoaming in vacuum with the vacuum degree being not less than-0.095 MPa to obtain an elastomer B material, and sealing and storing for later use.

3) Mixing the elastomer A, B material according to the weight ratio of 1.7: 1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the polyurethane elastomer into an oven with the temperature of 80 ℃ and curing for 2 hours to obtain the polyurethane elastomer.

Comparative example 2

3) Mixing an elastomer A, B material according to the weight ratio of 0.9: 1, uniformly mixing at room temperature, removing mechanical bubbles in vacuum, pouring the mixture into a die for sealing reaction, and taking out the mixture after 8 hours, wherein the vacuum degree is not less than-0.095 MPa. And finally, putting the mixture into an oven at 80 ℃ and curing for 2 hours to obtain the transparent polyurethane elastomer.

The moisture content in the examples of the invention and the comparative examples was measured by a karl fischer moisture meter. The performance test adopts the following equipment: shore hardness tester for testing elastomer hardness, universal tensile machine for testing tensile strength and elongation at break, and ultraviolet-visible spectrophotometer for measuring light transmittance, all operated according to conventional methods.

The elastomers of examples and comparative examples were subjected to the performance test by the above-mentioned method, and the results are shown in table 1:

TABLE 1 results of property characterization of examples and comparative examples

Tests show that the water content of the polyether polyol which is not strictly preserved in a waterproof way is generally between 2000 and 2500 ppm. In order to meet the use requirement, the water content in polyether polyol and other reaction components is reduced to 300-500 ppm by a complicated multi-time dehydration process in the conventional method, and the problem that chemical bubbles appear in the elastomer and on the surface of the elastomer is solved only by adopting a simple prepolymer conversion method and not dehydrating the polyether polyol in each embodiment of the invention. While examples 1-8 did not exhibit chemical bubbles, examples 9-13 were further tested for the effect of a gradient of water content on the polyurethane elastomer, and the bubble display results are shown in FIGS. 1-5. As can be seen from the figure, only very small amounts of bubbles were present in the polyether polyol at a water content of 3000ppm (FIG. 1), whereas the problem of chemical bubbles, which were not present, was avoided with the process of the invention when the water content was reduced to below 2500ppm (FIGS. 2-5). In addition, compared with the traditional method for accelerating the gelling process by increasing the using amount of the gelling catalyst, the operation time of each embodiment of the invention can be prolonged to 1-3h, and the method has great improvement compared with a comparative example, and is beneficial to meeting the requirements of downstream customers on the operation time, so that the stress in the elastomer is released in the curing process, and the mechanical property is improved.

The elastomers prepared in examples 1 to 13 include hard rubber and soft rubber, have a hardness span ranging from shore 33A to shore 86D, and have the advantage of wide adjustable range, so that the method can be widely applied to industry and used for producing polyurethane elastomers with different hardness requirements. From the test results, in addition to the effective removal of bubbles,

the soft gels prepared in examples 1-2 and 10-13 were superior to the soft gel prepared in comparative example 1 in both tensile strength and elongation at break, and the hard gels prepared in examples 3-8 were slightly inferior to the hard gel prepared in comparative example 2 in tensile strength, but were not much different in tensile strength and elongation at break, respectively, to the hard gel prepared in comparative example 2. In addition, the transparent polyurethane elastomer prepared by the method of the invention also has the advantage of good light transmission, and can meet the industrial application requirements equivalent to those of a comparative example.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.

Claims

1. A preparation process of a casting polyurethane elastomer is characterized by comprising the following steps:

1) reacting isocyanate with polyether polyol or polyester polyol in the presence of a tertiary amine catalyst, and adding an organic metal catalyst and a defoaming agent to prepare an elastomer material A; the adding amount of the isocyanate is 5-20 wt% of the polyether polyol or the polyester polyol in terms of mass ratio;

3) mixing A, B materials according to the mass ratio of 1: 1-3: 1, removing mechanical bubbles in vacuum, and carrying out sealing reaction to prepare a polyurethane elastomer;

after the preparation of the elastomer A material and the elastomer B material is finished, removing bubbles in vacuum, and sealing for later use;

the water content in the polyether polyol or polyester polyol is less than or equal to 3000 ppm.

2. The process for preparing a cast polyurethane elastomer according to claim 1, wherein in the step 1), the isocyanate is added in an amount of 5 to 10 wt% based on the mass ratio of the polyether polyol or the polyester polyol.

3. The preparation process of the casting polyurethane elastomer according to claim 1, wherein the polyurethane elastomer is put into an oven at 60-120 ℃ for curing after being prepared, and the operation time is 1-5 hours.

4. A process for preparing a cast polyurethane elastomer according to any one of claims 1 to 3, wherein in the preparation of the elastomer material A, the isocyanate preferentially reacts with water in the polyether polyol or polyester polyol under the action of the tertiary amine catalyst, and the moisture content involved in the reaction is 51 to 73 wt% of the total water content in the polyol.

5. The process for preparing a cast polyurethane elastomer according to any one of claims 1 to 3, wherein the polyether polyol or polyester polyol is one or more of polyester type or polyether type transparent polyols having a functionality of 2 to 5 and a molecular weight of 300 to 1000.

6. The process for preparing a cast polyurethane elastomer according to claim 5, wherein the polyether polyol or polyester polyol is one or more of polyester type or polyether type transparent polyol having a functionality of 2 to 5 and a molecular weight of 300 to 700.

7. The preparation process of the casting type polyurethane elastomer according to claim 6, wherein the polyether polyol or polyester polyol is one or more of polyether polyols R2303, R2304, R2403 and R2307.

8. The process for preparing a cast polyurethane elastomer according to claim 5, wherein the isocyanate is one or more of aliphatic or cycloaliphatic polyisocyanates.

9. The process for preparing a cast polyurethane elastomer according to claim 8, wherein the isocyanate is one or more of ADI isocyanates.

10. The process for preparing a cast polyurethane elastomer according to claim 9, wherein the isocyanate is hexamethylene 1, 6-diisocyanate and one or more of biuret, trimer, isophorone diisocyanate, 1, 4-cyclohexane diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate.

11. The preparation process of the casting type polyurethane elastomer according to claim 8, wherein the tertiary amine catalyst is used in an amount of 0.01 to 0.03 wt% based on the mass ratio of the polyether polyol or the polyester polyol; the tertiary amine catalyst is selected from one or more of pentamethyldiethylenetriamine and bis (dimethylaminoethyl) ether.

12. The preparation process of the cast polyurethane elastomer according to claim 11, wherein the tertiary amine catalyst is used in an amount of 0.01 to 0.02 wt% based on the mass ratio of the polyether polyol or the polyester polyol.

13. The process for preparing a cast polyurethane elastomer according to claim 11, wherein the tertiary amine catalyst is pentamethyldiethylenetriamine.

14. The process for preparing a cast polyurethane elastomer according to claim 11, wherein the amount of the organometallic catalyst is 0.08 to 0.15 wt% based on the mass ratio of the polyether polyol or polyester polyol; the organic metal catalyst is selected from one or more of organic bismuth catalysts or organic tin catalysts.

15. The process for preparing a cast polyurethane elastomer according to claim 14, wherein the organometallic catalyst is used in an amount of 0.10 to 0.15 wt% based on the mass ratio of the polyether polyol or polyester polyol.

16. The process for preparing a cast polyurethane elastomer according to claim 14, wherein the organometallic catalyst is selected from dibutyltin dilaurate or stannous octoate or bismuth neodecanoate.

17. The preparation process of the casting polyurethane elastomer according to claim 14, wherein the amount of the defoaming agent is 0.1-0.2 wt% of the polyether polyol or the polyester polyol in terms of mass ratio; the defoaming agent is an organic silicon defoaming agent.

18. The preparation process of the cast polyurethane elastomer according to claim 17, wherein the amount of the defoaming agent is 0.1 to 0.15 wt% of the polyether polyol or the polyester polyol in terms of mass ratio.

19. The process for preparing a cast polyurethane elastomer according to claim 17, wherein the defoamer is guangdong bang B-0599.