Polyurethane thermal insulation material for geothermal well oil pipes and its preparation method

Abstract

The present invention belongs to the technical field of polyurethane heat insulation materials, and specifically relates to a polyurethane heat insulation material for geothermal well oil pipes and a preparation method thereof. For the polyurethane heat insulation material for geothermal well oil pipes of the present invention, polyester polyol and polyether polyol are mixed and reacted with 4,4'-dicyclohexylmethane diisocyanate to fundamentally ensure the mechanical properties of the prepared polyurethane material. At the same time, 2,4-diamino-3,5-dimethylthiotoluene and 1,4-butanediamine are also added to further crosslink and chain-extend with isocyanate, promoting the formation of a more compact crosslinked network structure of the polyurethane material. In addition, a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is added as a filler to ensure the heat insulation performance of the prepared polyurethane material. Thus, through the synergistic effect between the raw materials, the mechanical properties and heat insulation performance of the prepared polyurethane material are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane heat insulation materials, and particularly relates to a polyurethane heat insulation material for geothermal well oil pipes and a preparation method thereof. Background Art

[0002] A geothermal well oil pipe is a pipe used in a geothermal well, and its main function is to transport underground hot water or geothermal steam from the geothermal well to the ground. Geothermal well oil pipes play a crucial role in the exploitation of geothermal energy. They not only need to have good heat insulation performance to reduce heat energy loss, but also need to have sufficient strength to adapt to the high temperature and high pressure environment of the geothermal well. In view of the serious heat loss and poor heat insulation effect of ordinary oil pipes, using insulated oil pipes instead of ordinary oil pipes for operation can greatly reduce steam heat loss.

[0003] A thermal insulation coating is a type of material that blocks or weakens the heat transfer process by using materials with low thermal conductivity to achieve the effect of heat insulation. Thermal insulation coatings are divided into organic thermal insulation coatings, inorganic thermal insulation coatings, and organic-inorganic composite thermal insulation coatings. Organic thermal insulation coatings mainly include polyurethane foam, polystyrene foam, and polysiloxane porous coatings; inorganic thermal insulation coatings mainly include perlite foam materials and SiO2 aerogel; organic-inorganic composite thermal insulation coatings mainly include hollow glass microsphere composite thermal insulation coatings, hollow SiO2 microsphere composite thermal insulation coatings, and porous ceramic composite thermal insulation coatings. Compared with inorganic thermal insulation coatings and organic-inorganic composite thermal insulation coatings, organic thermal insulation coatings have lower thermal conductivity and more excellent physical properties. Among organic thermal insulation coatings, polyurethane foam has become the most promising thermal insulation material due to its low cost, high mechanical strength, and low thermal conductivity. However, when the existing polyurethane foam is used for the insulation of geothermal well oil pipes, due to the application environment of high temperature and high pressure, its mechanical properties, thermal insulation properties, and temperature resistance are limited. Therefore, it is necessary to explore a new type of polyurethane heat insulation material for geothermal well oil pipes. Summary of the Invention

[0004] The purpose of the present invention is to provide a polyurethane heat insulation material for geothermal well oil pipes. The polyurethane heat insulation material has excellent mechanical properties and heat insulation properties; the present invention also provides a preparation method thereof at the same time.

[0005] The polyurethane heat insulation material for geothermal well oil pipes according to the present invention is composed of the following raw materials in parts by weight: 28 - 30 parts of bisphenol A polyether polyol, 15 - 17 parts of polycaprolactone diol, 32 - 34 parts of trimethylolpropane polyether polyol, 115.5 - 118.5 parts of 4,4'-dicyclohexylmethane diisocyanate, 2.8 - 3.0 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3 - 3.3 parts of 1,4-butanediamine, 1.50 - 1.62 parts of pentamethyldiethylenetriamine, 5 - 5.4 parts of water, 10 - 12 parts of a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber; wherein, the preparation method of the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber consists of the following steps: adding palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber into a mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol, stirring at a speed of 400 - 420 r / min for 48 - 50 min, then filtering by suction and washing with ethanol to remove the residual γ-methacryloxypropyltrimethoxysilane, and finally drying at 75 - 78 °C for 7 h to prepare the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber.

[0006] Among them:

[0007] The mass ratio of the mixture of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber to the volume of the mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol is 1:22, with the unit of g / mL.

[0008] The mass concentration of γ-methacryloxypropyltrimethoxysilane in the mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol is 1.7%.

[0009] The mass ratio of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fiber is 10 - 12 : 2.3 - 3.4 : 4.5 - 5.7.

[0010] The palygorskite, in terms of mass percentage, has the following chemical composition: SiO2 58.10%, MgO 17.24%, Al2O3 11.15%, Fe2O3 1.52%, CaO 0.76%, K2O 0.15%, Na2O 0.15%, loss on ignition 10.93%.

[0011] The bisphenol A polyether polyol has a functionality of 2, a hydroxyl value of 285.7 mgKOH / g, is produced by Huainan Cody Chemical Technology Co., Ltd., and has a grade of BSA-40.

[0012] The functionality of the polycaprolactone diol is 2, the molecular weight is 830, the hydroxyl value is 135 mg KOH / g, the manufacturer is Hunan Juren New Materials Co., Ltd., and the grade is 2083.

[0013] The functionality of the trimethylolpropane polyether polyol is 3, the hydroxyl value is 610 mg KOH / g, the manufacturer is Zhejiang Huangma New Materials Technology Co., Ltd., and the grade is HMP-510B.

[0014] The polyurethane heat insulation and preservation material for geothermal well oil pipes described in the present invention uses a mixture of bisphenol A polyether polyol, polycaprolactone diol, and trimethylolpropane polyether polyol as the polyol raw material. Trimethylolpropane polyether polyol has a high functionality and high hydroxyl value, enabling it to have more crosslinking points with -NCO groups, which can form a denser crosslinking network, thereby making the prepared polyurethane material have excellent mechanical strength and dimensional stability. The aromatic ring and carbon-oxygen chain structure in bisphenol A polyether polyol endow the polyurethane material with specific rigidity and toughness respectively, and it has good corrosion resistance in strong acid and strong base environments, thus improving the chemical resistance and heat resistance of the polyurethane material. Polycaprolactone diol plays the role of elastic crosslinking points during the preparation process. Its addition can improve the tensile strength and tear strength of the prepared polyurethane material and improve the temperature resistance of the polyurethane material. Thus, the interaction among the three polyols fundamentally ensures the mechanical strength of the prepared polyurethane material. Using 4,4'-dicyclohexylmethane diisocyanate as the raw material to react with the polyol ensures the mechanical properties of the prepared polyurethane material. Using 2,4-diamino-3,5-dimethylthiotoluene as the crosslinking agent and 1,4-butanediamine as the chain extender, the amino groups in 2,4-diamino-3,5-dimethylthiotoluene and the amino groups in 1,4-butanediamine can react with the isocyanate group (-NCO) to form urea bonds (-NH-CO-NH-), thereby rapidly expanding the molecular chain and increasing the crosslinking density of the polyurethane network. This crosslinking structure can significantly improve the mechanical strength, tear strength, and abrasion resistance of the polyurethane material. Using pentamethyldiethylenetriamine as the catalyst significantly increases the foaming speed of the polyurethane foam, shortens the foaming time, balances the overall foaming reaction, improves the cell structure, makes the cells more uniform and delicate, and ensures the uniformity and stability of the polyurethane material. Using water as the foaming agent and a mixture of modified palygorskite, phenolic hollow microspheres, and polyacrylonitrile pre-oxidized fibers as the filler, the synergistic effect of palygorskite, phenolic hollow microspheres, and polyacrylonitrile pre-oxidized fibers is utilized to improve the heat insulation and preservation performance of the polyurethane material. Among them, the addition of palygorskite can significantly improve the pore structure of the polyurethane material, making its pore diameter smaller and the distribution more uniform, thereby making the polyurethane material have better heat insulation performance. Phenolic hollow microspheres have a very low thermal conductivity. This low thermal conductivity characteristic enables phenolic hollow microspheres to form low thermal conductivity regions in the polyurethane material, effectively preventing heat transfer, thereby improving the heat insulation performance of the polyurethane material. In addition, the interior of the phenolic hollow microspheres is a hollow structure, and these closed pores can effectively reduce the convective heat transfer. The closed-cell phenolic hollow microspheres form a large number of cavities in the polyurethane material, further reducing the thermal conductivity of the polyurethane material. Polyacrylonitrile pre-oxidized fibers themselves have a low thermal conductivity, high strength, and high modulus. Its addition can enhance the heat insulation performance and mechanical properties of the prepared polyurethane material.Thus, the synergistic effect of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers fundamentally ensures the heat insulation performance of the prepared polyurethane material.

[0015] The preparation method of the polyurethane heat insulation and preservation material for geothermal well oil pipes according to the present invention comprises the following steps: adding bisphenol A polyether polyol, polycaprolactone diol, trimethylolpropane polyether polyol, water, 2,4-diamino-3,5-dimethylthiotoluene, 1,4-butanediamine, pentamethyldiethylenetriamine, and a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a reaction vessel and mixing evenly, then adding 4,4'-dicyclohexylmethane diisocyanate and mixing evenly, pouring into a mold preheated to 47 - 50 °C, stirring until foaming is stable, and then carrying out curing treatment to prepare the polyurethane heat insulation and preservation material for geothermal well oil pipes.

[0016] Among them:

[0017] The curing temperature is 55 - 57 °C, and the curing time is 2 - 2.3 h.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) For the polyurethane heat insulation and preservation material for geothermal well oil pipes according to the present invention, the polyester polyol and polyether polyol are used in combination and reacted with 4,4'-dicyclohexylmethane diisocyanate, which fundamentally ensures the mechanical properties of the prepared polyurethane material. At the same time, 2,4-diamino-3,5-dimethylthiotoluene and 1,4-butanediamine are also added to further crosslink and chain-extend with the isocyanate, promoting the formation of a more compact crosslinked network structure of the polyurethane material. In addition, a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is added as a filler to ensure the heat insulation performance of the prepared polyurethane material. Thus, the synergistic effect among the raw materials ensures the mechanical properties and heat insulation and preservation performance of the prepared polyurethane material.

[0020] (2) The preparation method of the polyurethane heat insulation and preservation material for geothermal well oil pipes according to the present invention has a simple process, wide sources of raw materials, easy control of parameters, and excellent performance of the prepared polyurethane heat insulation and preservation material. Specific Embodiments

[0021] The present invention will be further described below in conjunction with embodiments.

[0022] Example 1

[0023] The polyurethane heat insulation and preservation material for geothermal well oil pipes described in this Example 1 is composed of the following raw materials in parts by weight: 29 parts of bisphenol A polyether polyol, 16 parts of polycaprolactone diol, 33 parts of trimethylolpropane polyether polyol, 117 parts of 4,4'-dicyclohexylmethane diisocyanate, 2.9 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3.2 parts of 1,4-butanediamine, 1.56 parts of pentamethyldiethylenetriamine, 5.2 parts of water, a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers; among them, the preparation method of the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers consists of the following steps: adding palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and absolute ethanol, stirring at a speed of 410 r / min for 49 min, then filtering and washing with ethanol to remove the residual γ-methacryloyloxypropyltrimethoxysilane, and finally drying at 77 °C for 7 h to prepare the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers.

[0024] Among them:

[0025] The mass ratio of the mixture of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers to the volume of the mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and absolute ethanol is 1:22, with the unit of g / mL.

[0026] The mass concentration of γ-methacryloyloxypropyltrimethoxysilane in the mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and absolute ethanol is 1.7%.

[0027] The mass ratio of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is 11:2.85:5.1.

[0028] The manufacturer of the phenolic hollow microspheres is Shandong Shengquan Chemical Co., Ltd.

[0029] The manufacturer of the polyacrylonitrile pre-oxidized fibers is Shanghai Yibena Textile Technology Co., Ltd.

[0030] The palygorskite, in terms of mass percentage, has the following chemical composition: SiO2 58.10%, MgO 17.24%, Al2O3 11.15%, Fe2O3 1.52%, CaO 0.76%, K2O 0.15%, Na2O 0.15%, loss on ignition 10.93%.

[0031] The functionality of the bisphenol A polyether polyol is 2, the hydroxyl value is 285.7 mgKOH / g, the manufacturer is Huainan Cody Chemical Technology Co., Ltd., and the grade is BSA-40.

[0032] The functionality of the polycaprolactone diol is 2, the molecular weight is 830, the hydroxyl value is 135 mg KOH / g, the manufacturer is Hunan Juren New Materials Co., Ltd., and the grade is 2083.

[0033] The functionality of the trimethylolpropane polyether polyol is 3, the hydroxyl value is 610 mg KOH / g, the manufacturer is Zhejiang Huangma New Materials Technology Co., Ltd., and the grade is HMP-510B.

[0034] The preparation method of the polyurethane thermal insulation material for geothermal well oil pipes described in Example 1 of the present invention comprises the following steps: adding bisphenol A polyether polyol, polycaprolactone diol, trimethylolpropane polyether polyol, water, 2,4-diamino-3,5-dimethylthiotoluene, 1,4-butanediamine, pentamethyldiethylenetriamine, and a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a reaction vessel and mixing evenly, then adding 4,4'-dicyclohexylmethane diisocyanate and mixing evenly, pouring it into a mold preheated to 49 °C, stirring until the foaming is stable, and then carrying out a curing treatment to prepare the polyurethane thermal insulation material for geothermal well oil pipes.

[0035] Among them:

[0036] The curing temperature is 56 °C, and the curing time is 2.1 h.

[0037] Example 2

[0038] The polyurethane thermal insulation material for geothermal well oil pipes described in Example 2 of the present invention is composed of the following raw materials in parts by weight: 28 parts of bisphenol A polyether polyol, 15 parts of polycaprolactone diol, 34 parts of trimethylolpropane polyether polyol, 115.5 parts of 4,4'-dicyclohexylmethane diisocyanate, 2.8 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3 parts of 1,4-butanediamine, 1.50 parts of pentamethyldiethylenetriamine, 5.3 parts of water, 12 parts of a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers; among them, the preparation method of the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers comprises the following steps: adding palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and anhydrous ethanol, stirring at a speed of 420 r / min for 50 min, then filtering by suction and washing with ethanol to remove the residual γ-methacryloyloxypropyltrimethoxysilane, and finally drying at 78 °C for 7 h to prepare the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers.

[0039] Among them:

[0040] The mass ratio of the mixture of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers to the volume of the mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and absolute ethanol is 1:22, with the unit of g / mL.

[0041] The mass concentration of γ-methacryloyloxypropyltrimethoxysilane in the mixed solution composed of γ-methacryloyloxypropyltrimethoxysilane and absolute ethanol is 1.7%.

[0042] The mass ratio of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is 12:2.3:4.5.

[0043] The manufacturer of the phenolic hollow microspheres is Shandong Shengquan Chemical Co., Ltd.

[0044] The manufacturer of the polyacrylonitrile pre-oxidized fibers is Shanghai Yibena Textile Technology Co., Ltd.

[0045] The chemical composition of the palygorskite, in mass percentage, is as follows: SiO2 58.10%, MgO 17.24%, Al2O3 11.15%, Fe2O3 1.52%, CaO 0.76%, K2O 0.15%, Na2O 0.15%, loss on ignition 10.93%.

[0046] The functionality of bisphenol A polyether polyol is 2, the hydroxyl value is 285.7 mgKOH / g, the manufacturer is Huainan Cody Chemical Technology Co., Ltd., and the product number is BSA-40.

[0047] The functionality of polycaprolactone diol is 2, the molecular weight is 830, the hydroxyl value is 135 mgKOH / g, the manufacturer is Hunan Juren New Materials Co., Ltd., and the product number is 2083.

[0048] The functionality of trimethylolpropane polyether polyol is 3, the hydroxyl value is 610 mgKOH / g, the manufacturer is Zhejiang Huangma New Materials Technology Co., Ltd., and the product number is HMP-510B.

[0049] The preparation method of the polyurethane thermal insulation material for geothermal well oil pipes described in Example 2 consists of the following steps: adding bisphenol A polyether polyol, polycaprolactone diol, trimethylolpropane polyether polyol, water, 2,4-diamino-3,5-dimethylthiotoluene, 1,4-butanediamine, pentamethyldiethylenetriamine, and the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a reaction vessel and mixing evenly, then adding 4,4'-dicyclohexylmethane diisocyanate and mixing evenly, pouring into a mold preheated to 47°C, stirring until the foaming is stable, and then carrying out curing treatment to prepare the polyurethane thermal insulation material for geothermal well oil pipes.

[0050] Among them:

[0051] The aging temperature is 55 °C and the aging time is 2 h.

[0052] Example 3

[0053] The polyurethane heat insulation and thermal insulation material for geothermal well oil pipes described in this Example 3 is composed of the following raw materials in parts by weight: 30 parts of bisphenol A polyether polyol, 17 parts of polycaprolactone diol, 32 parts of trimethylolpropane polyether polyol, 118.5 parts of 4,4'-dicyclohexylmethane diisocyanate, 3.0 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3.3 parts of 1,4-butanediamine, 1.62 parts of pentamethyldiethylenetriamine, 5.4 parts of water, 10 parts of a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers; among them, the preparation method of the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers consists of the following steps: adding palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol, stirring at a speed of 400 r / min for 48 min, then filtering by suction and washing with ethanol to remove the residual γ-methacryloxypropyltrimethoxysilane, and finally drying at 75 °C for 7 h to prepare the mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers.

[0054] Among them:

[0055] The mass ratio of the mixture of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers to the volume of the mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol is 1:22, with the unit of g / mL.

[0056] The mass concentration of γ-methacryloxypropyltrimethoxysilane in the mixed solution composed of γ-methacryloxypropyltrimethoxysilane and absolute ethanol is 1.7%.

[0057] The mass ratio of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is 10:3.4:5.7.

[0058] The manufacturer of the phenolic hollow microspheres is Shandong Shengquan Chemical Co., Ltd.

[0059] The manufacturer of the polyacrylonitrile pre-oxidized fibers is Shanghai Yibena Textile Technology Co., Ltd.

[0060] The palygorskite, in terms of mass percentage, has the following chemical composition: SiO2 58.10%, MgO 17.24%, Al2O3 11.15%, Fe2O3 1.52%, CaO 0.76%, K2O 0.15%, Na2O 0.15%, loss on ignition 10.93%.

[0061] The functionality of bisphenol A polyether polyol is 2, the hydroxyl value is 285.7 mgKOH / g, the manufacturer is Huainan Cody Chemical Technology Co., Ltd., and the grade is BSA-40.

[0062] The functionality of polycaprolactone diol is 2, the molecular weight is 830, the hydroxyl value is 135 mgKOH / g, the manufacturer is Hunan Juren New Materials Co., Ltd., and the grade is 2083.

[0063] The functionality of trimethylolpropane polyether polyol is 3, the hydroxyl value is 610 mgKOH / g, the manufacturer is Zhejiang Huangma New Materials Technology Co., Ltd., and the grade is HMP-510B.

[0064] The preparation method of the polyurethane heat insulation and preservation material for geothermal well oil pipes described in Example 3 of the present invention consists of the following steps: adding bisphenol A polyether polyol, polycaprolactone diol, trimethylolpropane polyether polyol, water, 2,4-diamino-3,5-dimethylthiotoluene, 1,4-butanediamine, pentamethyldiethylenetriamine, and a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a reaction vessel and mixing evenly, then adding 4,4'-dicyclohexylmethane diisocyanate and mixing evenly, pouring into a mold preheated to 50 °C, stirring until the foaming is stable, and then carrying out a curing treatment to prepare the polyurethane heat insulation and preservation material for geothermal well oil pipes.

[0065] Among them:

[0066] The curing temperature is 57 °C and the curing time is 2.3 h.

[0067] Comparative Example 1

[0068] The preparation method of the polyurethane heat insulation and preservation material for geothermal well oil pipes described in this Comparative Example 1 is the same as that in Example 1, and the only difference lies in the raw material composition. The polyurethane heat insulation and preservation material for geothermal well oil pipes described in this Comparative Example 1 consists of the following raw materials in parts by weight: 29 parts of bisphenol A polyether polyol, 16 parts of polycaprolactone diol, 33 parts of trimethylolpropane polyether polyol, 117 parts of 4,4'-dicyclohexylmethane diisocyanate, 2.9 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3.2 parts of 1,4-butanediamine, 1.56 parts of pentamethyldiethylenetriamine, and 5.2 parts of water.

[0069] The performance of the polyurethane thermal insulation materials prepared in Examples 1-3 and Comparative Example 1 was tested. Among them, the thermal conductivity was tested in accordance with GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Guarded Hot Plate Method"; the compressive strength was tested in accordance with GB / T 8813-2020 "Rigid Cellular Plastics - Determination of Compressive Properties"; the density was tested in accordance with GB / T 6343-2009 "Cellular Plastics and Rubber - Determination of Apparent Density"; the dimensional stability was tested in accordance with SY / T 0415-96 "Technical Standard for Anti-Corrosion and Thermal Insulation Layers of Rigid Polyurethane Foam for Buried Steel Pipelines", the test temperature was 100 °C, and the test time was 96 h; the results are shown in Table 1 below.

[0070] Table 1 Performance Test Results of Polyurethane Thermal Insulation Materials

[0071]

Claims

1. A polyurethane thermal insulation material for geothermal well oil pipe, characterized by: The invention is composed of the following raw materials in parts by weight: 28-30 parts of bisphenol A polyether polyol, 15-17 parts of polycaprolactone diol, 32-34 parts of trimethylolpropane polyether polyol, 115.5-118.5 parts of 4,4'-dicyclohexylmethane diisocyanate, 2.8-3.0 parts of 2,4-diamino-3,5-dimethylthiotoluene, 3-3.3 parts of 1,4-butanediamine, 1.50-1.62 parts of pentamethyldiethylenetriamine, 5-5.4 parts of water, and 10-12 parts of a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers; wherein the modified The invention discloses a method for preparing a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers, comprising the following steps: adding palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a mixed solution of γ-methacryloxypropyltrimethoxysilane and anhydrous ethanol, stirring at a speed of 400-420 r / min for 48-50 min, then filtering and washing with ethanol to remove residual γ-methacryloxypropyltrimethoxysilane, and finally drying at 75-78° C. for 7 h to prepare a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers; in: The mass ratio of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers is 10-12: 2.3-3.4: 4.5-5.7; The functionality of bisphenol A polyether polyol is 2, and the hydroxyl value is 285.7 mgKOH / g; The functionality of polycaprolactone diol is 2, the molecular weight is 830, and the hydroxyl value is 135 mgKOH / g; The functionality of trimethylolpropane polyether polyol is 3, and the hydroxyl value is 610 mgKOH / g.

2. The polyurethane thermal insulation material for geothermal well oil pipe according to claim 1, characterized in that: The mass ratio of the mixture of palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers to the volume ratio of the mixed solution of γ-methacryloxypropyltrimethoxysilane and anhydrous ethanol is 1:22, and the unit is g / mL.

3. The polyurethane thermal insulation material for geothermal well oil pipe according to claim 1, characterized in that: The mass concentration of γ-methacryloxypropyltrimethoxysilane in the mixed solution of γ-methacryloxypropyltrimethoxysilane and anhydrous ethanol is 1.7%.

4. The polyurethane thermal insulation material for geothermal well oil pipe according to claim 1, characterized in that: The chemical composition of the palygorskite, in terms of mass percentage, is as follows: SiO2 58.10%, MgO 17.24%, Al2O3 11.15%, Fe2O3 1.52%, CaO 0.76%, K2O 0.15%, Na2O 0.15%, and loss on ignition 10.93%.

5. A method for preparing the polyurethane thermal insulation material for geothermal well oil pipe according to claim 1, characterized in that: The method comprises the following steps: adding bisphenol A polyether polyol, polycaprolactone diol, trimethylolpropane polyether polyol, water, 2,4-diamino-3,5-dimethylthiotoluene, 1,4-butanediamine, pentamethyldiethylenetriamine, a mixture of modified palygorskite, phenolic hollow microspheres and polyacrylonitrile pre-oxidized fibers into a reaction container and mixing them evenly; then adding 4,4'-dicyclohexylmethane diisocyanate and mixing evenly; pouring the mixture into a mold preheated to 47-50°C, stirring the mixture until the foaming is stable, and then subjecting the mixture to aging treatment to prepare a polyurethane thermal insulation material for geothermal well oil pipes.

6. The method for preparing the polyurethane thermal insulation material for geothermal well oil pipe according to claim 5, characterized in that: The aging temperature is 55-57°C and the aging time is 2-2.5h.

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