Silicone oligomer intercalated montmorillonite and preparation method thereof, modified hot-melt boron phenolic resin and preparation method thereof

Abstract

The invention discloses a kind of organosilicon oligomer intercalation montmorillonite and preparation method, modified hot-melt boron phenolic resin and preparation method, the preparation method of hot-melt boron phenolic resin, comprising the following steps: adding aldehyde to the mixture of molten phenol and organosilicon oligomer intercalation montmorillonite, adjusting pH, reacting at 50-70 DEG C for 1-5h, adding boric acid derivative, adding modifier after reaction at 90-120 DEG C, stirring evenly, and then performing vacuum distillation until the gel time of the product at 180±1 DEG C is 120-320s. The use of organosilicon oligomer intercalation in the hot-melt boron phenolic resin prepared by the present invention increases the spacing of the two-dimensional montmorillonite lamellae, and the larger interlayer spacing enables the phenolic resin to be in situ polycondensed between the montmorillonite layers to realize the formation of a montmorillonite exfoliation structure; at the same time, the lamellar structure of the montmorillonite extends the heat transfer channel, improves the initial thermal decomposition temperature, thermal stability and mechanical properties of the resin cured product.

Description

Technical Field

[0001] The present invention belongs to the field of phenolic resins, and in particular relates to an organosilicon oligomer intercalated montmorillonite and a preparation method thereof, and a modified hot-melt boron phenolic resin and a preparation method thereof. Background Art

[0002] To meet the increasingly demanding service environments of new rocket engines and spacecraft, higher requirements are being placed on thermal protection materials for ablation and thermal flow environments. Resin-based composite materials used in ablation applications must exhibit outstanding high-temperature and ablation resistance. Compared to conventional phenolic resins, the boron element in the boron phenolic resin matrix blocks the easily oxidized phenolic hydroxyl groups in the phenolic resin, forming high-energy BOC bonds. Simultaneously, the boron compound cross-links itself to form a BOB structure, and during pyrolysis, a liquid B2O3 protective film is formed, further enhancing the resin's high-temperature resistance. In summary, boron phenolic resins possess superior heat resistance, ablation resistance, and mechanical properties, making them suitable as excellent ablation-resistant material matrices with potential applications in rockets, missiles, and spacecraft. However, the large amount of trifunctional boron structures in boron phenolic resins makes their synthesis difficult to control and the product brittle, limiting their large-scale production and application. Two-dimensional materials can form covalent interactions with the resin matrix and a certain degree of meshing with the cross-linked network, which can hinder the movement of molecular chains and help improve the rigidity of the matrix. Furthermore, when subjected to external impact forces, the introduction of two-dimensional materials can change the direction of cracks, while enhancing crack bridging and forming shear bands between them and the thermosetting resin, thereby improving the toughness of the matrix. However, two-dimensional nanomaterials are subject to van der Waals forces and have a strong tendency to self-aggregate, which may reduce or even worsen the performance of the resin.

[0003] Polymer / layered silicate materials are organic-inorganic materials with an organic polymer as the matrix and layered silicate as the dispersed phase. The interlayer spacing of the silicate is exploited to allow the insertion of polymer macromolecules, forming micro- and nano-scale layered materials. However, montmorillonite has a strong tendency to self-aggregate, and the large number of inorganic ions between the layers are hydrophilic. This makes it difficult for polymer monomers to be inserted into unmodified layered inorganic materials and then polymerize again. Therefore, it is necessary to introduce organosilicon oligomers to increase the interlayer spacing and prevent aggregation. Organic cations also make the montmorillonite organic, making it lipophilic, making the insertion or exfoliation of polymers possible.

[0004] Fiber-reinforced phenolic resin-based composites, as ablative thermal protection materials, offer advantages such as easy molding, short processing cycles, and excellent thermal insulation properties. They are primarily produced through a phenolic resin prepreg winding and hot pressing process. Phenolic prepregs are primarily prepared by solution impregnation and hot melt impregnation. Compared to the solution impregnation method (wet process), the hot melt prepreg method (dry process) offers low volatile matter content, controllable resin content, and excellent batch stability. The resulting composites have low porosity, strong mechanical properties, and excellent dimensional stability. The hot melt prepreg method requires the resin to exhibit good moldability and arbitrarily bendable at room temperature, while maintaining a low viscosity for extended periods at the melting temperature.

[0005] Traditional boron phenolic resin has a high degree of cross-linking and a large molecular weight. At the melting temperature, the viscosity of the resin increases rapidly, it is easy to gel, and the film is brittle and easy to fall off, which makes it difficult to meet the requirements of the hot melt prepreg processing technology.

[0006] In view of this, there is an urgent need to seek an improved preparation method for hot-melt boron phenolic resin, which can optimize the synthesis process, simplify the synthesis steps, improve the thermal and mechanical properties of the resin and meet the requirements of hot-melt processing technology to adapt to the wider application of boron phenolic resin. Summary of the Invention

[0007] In order to optimize the thermal and mechanical properties of resins in the existing technology and meet the process requirements of hot-melt processing, the present invention provides an organosilicon oligomer intercalated montmorillonite and a preparation method, a modified hot-melt boron phenolic resin and a preparation method. The modified hot-melt boron phenolic resin prepared by this method has low brittleness and good film-forming properties, and can meet the requirements of the hot-melt prepreg processing technology.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing organosilicon oligomer intercalated montmorillonite comprises the following steps:

[0010] ball milling a mixture of organosilicon oligomer, montmorillonite and water to obtain organosilicon oligomer intercalated montmorillonite;

[0011] Furthermore, the mass ratio of the organosilicon oligomer to the montmorillonite is 1-10:10-1.

[0012] Furthermore, the organosilicon oligomer is one or more of methyl silicone oil, phenyl silicone oil, amino silicone oil, epoxy silicone oil and polyether modified silicone oil with a molecular weight of 1000-5000 g / mol;

[0013] The montmorillonite is one or more of organic quaternary ammonium salt intercalated montmorillonite, sodium montmorillonite, calcium montmorillonite and acid activated montmorillonite.

[0014] Furthermore, the ball milling speed is 100-400 rpm, and the time is 10-30 h.

[0015] A silicone oligomer intercalated montmorillonite.

[0016] A method for preparing a hot-melt boron phenolic resin modified by an organosilicon oligomer intercalated montmorillonite comprises the following steps:

[0017] The molten phenol and the organosilicon oligomer intercalated montmorillonite are mixed evenly, and then aldehyde is added, the pH is adjusted to 7-8, and the reaction is carried out at 50-70°C for 1-5 hours to obtain an intermediate product;

[0018] A boric acid derivative is added to the intermediate product, reacted at 90-120° C. for 0.5-6 hours, and a modifier is added after reduced pressure distillation. The mixture is stirred evenly, and reduced pressure distillation is performed again until the gel time of the product at 180±1° C. reaches 120-320 seconds to obtain an organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin.

[0019] Furthermore, the molar ratio of phenol, aldehyde and boron compound is 10-200:12-300:1-60; the weight ratio of phenol, organosilicon oligomer intercalated montmorillonite and modifier is 100:1-10:1-30.

[0020] Furthermore, the molar ratio of phenol, aldehyde and boron compound is 100:110-150:1-60; the weight ratio of phenol, organosilicon oligomer intercalated montmorillonite and modifier is 100:1-5:1-20.

[0021] Furthermore, the phenol is one or both of monohydric phenol and dihydric phenol; the boron compound is boric acid or a boric acid derivative;

[0022] Furthermore, the monohydric phenol is one or more of phenol, o-cresol, m-cresol, p-cresol, α-naphthol, β-naphthol and 4-hydroxymethylphenol; the dihydric phenol is one or more of o-catechol, resorcinol, hydroquinone, bisphenol A and bisphenol F;

[0023] Boric acid derivatives include one or more of p-boric acid, phenylboric acid, hydroxymethylphenylboric acid, hydroxyphenylboric acid, biphenylboric acid, borax, sodium borate, diphenylboric acid, methylphenylboric acid, dimethylphenylboric acid, methoxyphenylboric acid, isopropylphenylboric acid, ethoxyphenylboric acid, 1,4-phenylenediboric acid, ethylphenylboric acid, butylphenylboric acid, 2,4,6-triphenylboroxine and 3-hydroxyphenylboric acid.

[0024] Furthermore, the aldehyde is one or more of formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, trioxymethylene and paraformaldehyde;

[0025] Modifiers include polyvinyl acetal, thermoplastic phenolic resin, polyamide, epoxy resin E 20 Epoxy resin E 44Epoxy resin E 51 Epoxy resin F 44 With epoxy resin F 51 One or more of;

[0026] The pH is adjusted using one or more of NaOH, NH3·H2O and Ba(OH)2.

[0027] A silicone oligomer intercalated montmorillonite modified hot-melt boron phenolic resin with an initial decomposition temperature T 5% The temperature is 426-500℃, the residual carbon rate is 72.1-80.0%, the viscosity at 70℃ is 28693-66548mPa·s, and the impact strength is 2.6-3.8KJ·m -2 , the bending strength is 57.2-64.6MPa.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention first introduces organosilicon oligomers into the interlayers of montmorillonite through ball milling and intercalation. This increases the interlayer spacing of the silicate sheets while simultaneously transforming the montmorillonite from hydrophilic to lipophilic. This resolves the montmorillonite's agglomeration problem and makes it easier for the monomers to polymerize and delaminate between the layers. This allows the montmorillonite to be dispersed at a micro-nanoscale within the resin matrix, resulting in a highly strong and tough boron phenolic / montmorillonite material.

[0030] The addition of thermoplastic phenolic resin and epoxy resin modifiers during in-situ synthesis effectively addresses the poor film-forming and brittle nature of conventional boron phenolic resins. The resulting resin is non-sticky, non-degradable, and bendable at room temperature. It also maintains a low viscosity for extended periods at film-coating temperatures, making it suitable for hot-melt prepreg processes. The trifunctional boron structure in the boron phenolic resin of the present invention provides a large number of cross-linking sites for the resin matrix while also enhancing the resin's brittleness. Furthermore, the presence of a large number of rigid benzene ring structures within the boron phenolic resin requires toughening and modification. The present invention applies the nano effect and the strong interfacial interaction between nanoparticles and the polymer matrix to prepare a boron phenolic / montmorillonite nanocomposite material to meet the application scenarios of high strength and toughness of boron phenolic resin. At the same time, in order to solve the self-aggregation tendency of montmorillonite due to van der Waals force, it is easier for monomers to enter the silicate interlayer polymerization and peeling. An organosilicon oligomer is inserted into the montmorillonite interlayer in advance by means of ball milling, which increases the interlayer spacing of montmorillonite and converts montmorillonite from hydrophilic to lipophilic, making polymer insertion and peeling possible. Therefore, the phenol and aldehyde in the system smoothly enter the montmorillonite layer of the organosilicon oligomer intercalation through diffusion and intermolecular forces, and initiate polymerization between the layers. The huge heat released during polymerization overcomes the Coulomb force between the montmorillonite layers to peel them off, thereby dispersing the montmorillonite in the resin matrix at a nanoscale, obtaining a high-strength and tough boron phenolic / montmorillonite material, i.e., a modified hot-melt boron phenolic resin, and overcoming the problems of traditional boron phenolic resin being brittle, poor film-forming, and difficult to meet the requirements of hot-melt prepreg processing technology.

[0031] The synthesizing method of the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin prepared by the present invention is simple, the reaction process is stable and controllable, and the process is environmentally friendly. It is suitable for large-scale production and has good application prospects in the fields of ablation heat protection, refractory materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The montmorillonite and organosilicon oligomer intercalated montmorillonite in the present invention are scanned at a speed of 3°·min -1 , X-ray diffraction pattern in the scanning range of 0-10°.

[0033] Figure 2 2 are TGA curves of the boron phenolic resin cured products in Example 8, Comparative Example 1 and Comparative Example 2 of the present invention under a nitrogen atmosphere.

[0034] Figure 3 Graph showing mechanical data of carbon fiber composite materials prepared from boron phenolic resins in Example 8, Comparative Example 1, and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0035] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention may be implemented in a variety of different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0036] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin provided by the present invention comprises the following components in terms of molar ratio:

[0037] 10-200 parts of phenol;

[0038] 12-300 parts of aldehyde;

[0039] 1-60 parts of a boron compound;

[0040] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin further comprises an organosilicon oligomer intercalated montmorillonite and a modifier, and the relationship between the amount of the modifier and the phenol is as follows:

[0041] 100 parts by weight of phenol;

[0042] 1-10 parts by weight of organosilicon oligomer intercalated montmorillonite;

[0043] 1-30 parts by weight of a modifier;

[0044] Preferably, the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin comprises the following components in molar ratio:

[0045] 100 parts of phenol;

[0046] 110-150 parts of aldehyde;

[0047] 1-40 parts of a boron compound;

[0048] Preferably, the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin further comprises organosilicon oligomer intercalated montmorillonite and a modifier; the amount of the organosilicon oligomer intercalated montmorillonite, the modifier and the phenol is as follows:

[0049] 100 parts by weight of phenol;

[0050] 1-5 parts by weight of organosilicon oligomer intercalated montmorillonite;

[0051] 1-20 parts by weight of a modifier;

[0052] Preferably, the phenol is one or both of monohydric phenol and dihydric phenol; the monohydric phenol is one or more of phenol, o-cresol, m-cresol, p-cresol, α-naphthol, β-naphthol and 4-hydroxymethylphenol; the dihydric phenol is one or more of o-catechol, resorcinol, hydroquinone, bisphenol A and bisphenol F.

[0053] The aldehyde is one or more of formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, trioxymethylene and paraformaldehyde;

[0054] The boron compound is boric acid or a boric acid derivative;

[0055] The boric acid derivatives include one or more of phenylboronic acid, hydroxymethylphenylboronic acid, hydroxyphenylboronic acid, biphenylboronic acid, borax, sodium borate, diphenylboronic acid, methylphenylboronic acid, dimethylphenylboronic acid, methoxyphenylboronic acid, isopropylphenylboronic acid, ethoxyphenylboronic acid, 1,4-phenylenediboronic acid, ethylphenylboronic acid, butylphenylboronic acid, 2,4,6-triphenylboroxine and 3-hydroxyphenylboronic acid.

[0056] The modifier includes polyvinyl acetal, thermoplastic phenolic resin, polyamide, epoxy resin E 20 Epoxy resin E 44 Epoxy resin E 51 Epoxy resin F 44 With epoxy resin F 51 One or more of .

[0057] The preparation method of the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of the present invention comprises the following steps:

[0058] Preparation of organosilicon oligomer intercalated montmorillonite:

[0059] The organosilicon oligomer, montmorillonite, and deionized water are blended in a selected proportion and milled in a planetary ball mill at 100-400 rpm for 10-30 hours. After milling, the mixture is washed with 5-10 times the amount of deionized water and centrifuged. The precipitate is removed, dried, and ground to obtain organosilicon oligomer-intercalated montmorillonite. The mass ratio of organosilicon oligomer to montmorillonite is 1-10:10:1. The organosilicon oligomer comprises one or more of methyl silicone oil, phenyl silicone oil, amino silicone oil, epoxy silicone oil, and polyether-modified silicone oil (Jinan Xinglong Chemical Co., Ltd.) with a molecular weight of 1000-5000 g / mol. The montmorillonite comprises one or more of organic quaternary ammonium salt-intercalated montmorillonite, sodium montmorillonite, calcium montmorillonite, and acid-activated montmorillonite (DKSH Jiahui Zhengxing Chemical Shanghai Co., Ltd.).

[0060] Preparation of hot-melt boron phenolic resin modified by organosilicon oligomer intercalated montmorillonite:

[0061] In a molten state of phenol, an organosilicon oligomer intercalated montmorillonite is added and mixed for 1-5 hours, and then a certain weight portion of aldehyde is added, and the pH is adjusted to 7-8 by an alkaline catalyst and the reaction is carried out at 50-70°C for 1-5 hours to obtain an intermediate product; then, a selected portion of a boric acid derivative is added to the intermediate product, and the reaction is carried out at 90-120°C for 0.5-6 hours. After removing by-products by reduced pressure distillation, a modifier is added thereto, stirred, and mixed for 0.5 hours, and then vacuum dehydration is continued and the gel time is tested. When the gel time of the resin at 180±1°C reaches 120-320 seconds, the reaction is terminated to obtain an organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin.

[0062] The alkaline catalyst is one or more of NaOH, NH3·H2O and Ba(OH)2.

[0063] Preferably, the preparation method of the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin specifically comprises the following steps:

[0064] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 1-5 hours, and then adding the aldehyde, adjusting the pH to 7-8 using an alkaline catalyst, slowly heating to 50-70°C, and reacting for 1-5 hours to obtain an intermediate product A;

[0065] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 100-120° C. for 0.5-6 h to obtain an intermediate product B;

[0066] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0067] (4) When the temperature reaches 50-80°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 120-320s, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0068] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0069] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0070] Example 1

[0071] The organosilicon oligomer intercalated montmorillonite of this embodiment includes the following components by weight: 10 parts of montmorillonite, 10 parts of organosilicon oligomer and 20 parts of deionized water.

[0072] The montmorillonite is sodium montmorillonite, and the organosilicon oligomer is epoxy-functionalized organosilicon oligomer (produced by Dachang Hua Jiahui Zhengxing Chemical Shanghai Co., Ltd.), with a molecular weight of 1000-2000 g / mol.

[0073] The preparation method is as follows:

[0074] Montmorillonite, organosilicon oligomer and deionized water are taken in selected portions, a certain mass of porcelain balls are added and placed in a planetary ball mill at 200 rpm for 20 hours. The product is taken out, washed with deionized water, centrifuged, and the lower precipitate is taken out, dried and ground to obtain organosilicon oligomer intercalated montmorillonite.

[0075] Example 2

[0076] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 150 parts of aldehyde, and 20 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 5 parts of organosilicon oligomer intercalated montmorillonite (prepared in Example 1), and 20 parts of modifier.

[0077] The phenol is monohydric phenol, the monohydric phenol is phenol; the aldehyde is paraformaldehyde; the boron compound is paraboric acid; the modifier is a thermoplastic phenolic resin and E in a mass ratio of 9:1. 51 A mixture of epoxy resins.

[0078] The preparation method is as follows:

[0079] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, and then adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 4 hours to obtain an intermediate product A;

[0080] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 110° C. for 3 h to obtain an intermediate product B;

[0081] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0082] (4) When the temperature reaches 50-80°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 120-320s, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0083] Example 3

[0084] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 140 parts of aldehyde, and 25 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 5 parts of organosilicon oligomer intercalated montmorillonite, and 20 parts of modifier.

[0085] Wherein, the phenol is monohydric phenol, the monohydric phenol is phenol; the aldehyde is paraformaldehyde; the boron compound is paraboric acid; the modifier is thermoplastic phenolic resin and E 51 A mixture of epoxy resins.

[0086] The preparation method is as follows:

[0087] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 3 hours to obtain an intermediate product A;

[0088] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 110° C. for 2 h to obtain an intermediate product B;

[0089] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0090] (4) When the temperature reaches 70°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 120-320s, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0091] Example 4

[0092] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 110 parts of aldehyde, and 5 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 3 parts of organosilicon oligomer intercalated montmorillonite, and 20 parts of modifier.

[0093] Wherein, the phenol is monohydric phenol, the monohydric phenol is phenol; the aldehyde is paraformaldehyde; the boron compound is paraboric acid; the modifier is thermoplastic phenolic resin and E 51 A mixture of epoxy resins.

[0094] The preparation method is as follows:

[0095] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, and then adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 4 hours to obtain an intermediate product A;

[0096] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 100° C. for 4 h to obtain an intermediate product B;

[0097] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0098] (4) When the temperature reaches 50-80°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 120-320s, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0099] Example 5

[0100] The low-free-formaldehyde hot-melt boron phenolic resin of this embodiment comprises the following components, calculated by molar ratio: 100 parts of phenol, 120 parts of aldehyde, and 25 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 3 parts of organosilicon oligomer intercalated montmorillonite, and 15 parts of modifier.

[0101] Wherein, the phenol is monohydric phenol, the monohydric phenol is phenol; the aldehyde is paraformaldehyde; the boron compound is paraboric acid; the modifier is thermoplastic phenolic resin and E 51 A mixture of epoxy resins.

[0102] Its preparation method is:

[0103] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing at 50°C for 3 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 65°C, and reacting for 4 hours to obtain an intermediate product A;

[0104] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 95° C. for 4 h to obtain an intermediate product B;

[0105] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0106] (4) When the temperature reaches 70°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 200 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0107] Example 6

[0108] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 130 parts of aldehyde, and 10 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 2 parts of organosilicon oligomer intercalated montmorillonite, and 10 parts of modifier.

[0109] Wherein, the phenol is phenol; the aldehyde is paraformaldehyde powder; the boron compound is boric acid; the modifier is thermoplastic phenolic resin and E 44 A mixture of epoxy resins.

[0110] Its preparation method is:

[0111] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing at 50°C for 2 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 60°C, and reacting for 5 hours to obtain an intermediate product A;

[0112] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 110° C. for 3 h to obtain an intermediate product B;

[0113] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0114] (4) When the temperature reaches 70°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 200 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0115] Example 7

[0116] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 120 parts of aldehyde, and 15 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 5 parts of organosilicon oligomer intercalated montmorillonite, and 20 parts of modifier.

[0117] Wherein, the phenol is phenol; the aldehyde is paraformaldehyde powder; the boron compound is boric acid; the modifier is thermoplastic phenolic resin and E 44 A mixture of epoxy resins.

[0118] Its preparation method is:

[0119] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring, mixing at 50°C for 3 hours, adding the aldehyde in two portions, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 4 hours to obtain an intermediate product A;

[0120] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 90° C. for 6 h to obtain an intermediate product B;

[0121] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0122] (4) When the temperature reaches 60°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 240 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0123] Example 8

[0124] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 120 parts of aldehyde, and 30 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 5 parts of organosilicon oligomer intercalated montmorillonite, and 20 parts of modifier.

[0125] Wherein, the phenol is phenol; the aldehyde is paraformaldehyde powder; the boron compound is boric acid; the modifier is thermoplastic phenolic resin and E 51 A mixture of epoxy resins.

[0126] Its preparation method is:

[0127] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring, mixing at 50°C for 3 hours, adding the aldehyde in two portions, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 5 hours to obtain an intermediate product A;

[0128] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 105° C. for 3.5 hours to obtain an intermediate product B;

[0129] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0130] (4) When the temperature reaches 60°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 300 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0131] Example 9

[0132] The organosilicon oligomer intercalated montmorillonite of this embodiment includes the following components by weight: 1 part of montmorillonite, 10 parts of organosilicon oligomer and 20 parts of deionized water.

[0133] Wherein, the montmorillonite is organic quaternary ammonium salt intercalated montmorillonite, and the organosilicon oligomer is methyl silicone oil with a molecular weight of 1000-2000 g / mol.

[0134] The preparation method is as follows:

[0135] Montmorillonite, organosilicon oligomer and deionized water are taken in selected portions, a certain mass of porcelain balls are added and placed in a planetary ball mill at 100 rpm for 30 hours. The product is taken out, washed with deionized water, centrifuged, and the lower precipitate is taken out, dried and ground to obtain organosilicon oligomer intercalated montmorillonite.

[0136] Example 10

[0137] The organosilicon oligomer intercalated montmorillonite of this embodiment includes the following components by weight: 10 parts of montmorillonite, 2 parts of organosilicon oligomer and 20 parts of deionized water.

[0138] The montmorillonite is calcium-based montmorillonite, and the organosilicon oligomer is a mixture of amino silicone oil and polyether modified silicone oil (Jinan Xinglong Chemical Co., Ltd.) in a mass ratio of 1:1. The molecular weight of the amino silicone oil and the polyether modified silicone oil is 1000-2000 g / mol.

[0139] The preparation method is as follows:

[0140] Montmorillonite, organosilicon oligomer and deionized water are taken in selected portions, a certain mass of porcelain balls are added and placed in a planetary ball mill at 300 rpm for 15 hours. The product is taken out, washed with deionized water, centrifuged, and the lower precipitate is taken out, dried and ground to obtain organosilicon oligomer intercalated montmorillonite.

[0141] Example 11

[0142] The organosilicon oligomer intercalated montmorillonite of this embodiment includes the following components by weight: 10 parts of montmorillonite, 1 part of organosilicon oligomer and 20 parts of deionized water.

[0143] The montmorillonite is a mixture of acid-activated montmorillonite (DKSH Jiahui Zhengxing Chemical Shanghai Co., Ltd.) and organic quaternary ammonium salt intercalated montmorillonite in a mass ratio of 1:1, and the organosilicon oligomer is phenyl silicone oil with a molecular weight of 1000-2000 g / mol.

[0144] The preparation method is as follows:

[0145] Montmorillonite, organosilicon oligomer and deionized water are taken in selected portions, a certain mass of porcelain balls are added and placed in a planetary ball mill at 400 rpm for 10 hours. The product is taken out, washed with deionized water, centrifuged, and the lower precipitate is taken out, dried and ground to obtain organosilicon oligomer intercalated montmorillonite.

[0146] Example 12

[0147] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 10 parts of phenol, 12 parts of aldehyde, and 1 part of boron compound; calculated by weight ratio: 100 parts of phenol, 1 part of organosilicon oligomer intercalated montmorillonite (prepared in Example 1), and 1 part of modifier.

[0148] The phenol is a monophenol, which is o-benzol; the aldehyde is a mixture of trioxymethylene and polyformaldehyde in a molar ratio of 1:1; the boron compound is phenylboric acid; and the modifier is polyvinyl acetal in a mass ratio of 1:1.

[0149] The preparation method is as follows:

[0150] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 2 hours to obtain an intermediate product A;

[0151] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 90° C. for 6 h to obtain an intermediate product B;

[0152] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0153] (4) When the temperature reaches 50°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 120 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0154] Example 13

[0155] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 200 parts of phenol, 300 parts of aldehyde, and 40 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 5 parts of organosilicon oligomer intercalated montmorillonite (prepared in Example 1), and 30 parts of modifier.

[0156] The phenol is a dihydric phenol, which is a mixture of catechol and bisphenol A in a molar ratio of 1:1; the aldehyde is a mixture of butyraldehyde and glutaraldehyde in a molar ratio of 1:1; the boron compound is a mixture of hydroxymethylphenylboric acid and hydroxyphenylboric acid in a molar ratio of 1:1; the modifier is a mixture of polyamide and epoxy resin E in a mass ratio of 1:1. 20 mixture.

[0157] The preparation method is as follows:

[0158] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, adding the aldehyde, adjusting the pH to 7 using an alkaline catalyst, slowly heating to 50°C, and reacting for 5 hours to obtain an intermediate product A;

[0159] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 120° C. for 0.5 h to obtain an intermediate product B;

[0160] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0161] (4) When the temperature reaches 80°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 320 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0162] Example 14

[0163] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 100 parts of phenol, 140 parts of aldehyde, and 20 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 8 parts of organosilicon oligomer intercalated montmorillonite (prepared in Example 1), and 20 parts of modifier.

[0164] The phenol is a monohydric phenol, which is a mixture of 4-hydroxymethylphenol and β-naphthol in a molar ratio of 1:1; the aldehyde is acetaldehyde; the boron compound is a mixture of biphenylboric acid, borax, sodium borate, and diphenylboric acid in a molar ratio of 1:1:1:1; the modifier is an epoxy resin E in a mass ratio of 1:1 51 With epoxy resin F 44 mixture.

[0165] The preparation method is as follows:

[0166] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 70°C, and reacting for 1 hour to obtain an intermediate product A;

[0167] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 100° C. for 3 h to obtain an intermediate product B;

[0168] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0169] (4) When the temperature reaches 60°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 180 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0170] Example 15

[0171] The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of this embodiment includes the following components, calculated by molar ratio: 110 parts of phenol, 110 parts of aldehyde, and 60 parts of boron compound; calculated by weight ratio: 100 parts of phenol, 10 parts of organosilicon oligomer intercalated montmorillonite (prepared in Example 1), and 10 parts of modifier.

[0172] The phenol is a monohydric phenol, which is a mixture of 4-hydroxymethylphenol and β-naphthol in a molar ratio of 1:1; the aldehyde is formaldehyde; the boron compound is a mixture of methylphenylboric acid, dimethylphenylboric acid, methoxyphenylboric acid, isopropylphenylboric acid, ethoxyphenylboric acid, 1,4-phenylenediboric acid, ethylphenylboric acid, butylphenylboric acid, 2,4,6-triphenylboroxine and 3-hydroxyphenylboric acid in a molar ratio of 1:1:1:11:1:1:1:1; the modifier is epoxy resin F 51 .

[0173] The preparation method is as follows:

[0174] (1) Taking the phenol in selected portions, heating the phenol until it is melted, adding the selected portion of the organosilicon oligomer intercalated montmorillonite prepared by ball milling under stirring conditions, mixing for 3 hours, adding the aldehyde, adjusting the pH to 8 using an alkaline catalyst, slowly heating to 65°C, and reacting for 3 hours to obtain an intermediate product A;

[0175] (2) adding a selected amount of a boronic acid derivative to the intermediate product A obtained in step (1), and reacting under reflux at 110° C. for 2 h to obtain an intermediate product B;

[0176] (3) removing the water generated by the reaction by distilling the intermediate product obtained in step (2) under reduced pressure at 90-110°C;

[0177] (4) When the temperature reaches 70°C in step (3), add the modifier, stir, and mix for 30 minutes, then continue to vacuum dehydration and test the gel time. When the gel time of the resin at 180±1°C reaches 260 seconds, the reaction is completed to obtain a hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite.

[0178] Comparative Example 1

[0179] The hot-melt boron phenolic resin of this comparative example has the same composition as that of Example 8, except that the montmorillonite is not intercalated with organosilicon oligomer, and is prepared by the same method as in Example 8.

[0180] Comparative Example 2

[0181] The boron phenolic resin in this comparative example has the same composition as that in Example 8, except that the organosilicon oligomer intercalated montmorillonite is not included, and is prepared using the same method as in Example 8.

[0182] Effect verification:

[0183] In order to verify the technical effect of the organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin of the present invention, the boron phenolic resins prepared in Examples 2-8, Comparative Examples 1 and 2 were subjected to the following experiments:

[0184] The interlayer spacing of montmorillonite and montmorillonite intercalated with organosilicon oligomer was tested by X-ray diffraction.

[0185] Take the boron phenolic resin to be tested, and after curing, use a thermogravimetric analyzer (TG) to test the residual carbon rate of the resin at 800°C to simply judge the thermal stability of the resin.

[0186] The thermal and mechanical properties of the resin matrices of the examples and comparative examples, as well as their viscosity at hot melt processing temperatures, are shown in the following table. The boron phenolic resin to be tested was pressed into carbon fiber composites according to the national standard GB / T 9341-2008, and the impact strength and tensile strength of the composites were tested on a universal testing machine.

[0187] The experimental results are as follows:

[0188]

[0189] The temperature at which the weight loss is 5% is defined as the initial decomposition temperature T 5% .

[0190] According to the above table, the modified boron phenolic resin has a suitable viscosity at 70°C, a certain fluidity and processing window, and is suitable for hot melt prepreg method.

[0191] The crystal structure of unmodified montmorillonite and montmorillonite after intercalation of organosilicon oligomers was characterized by X-ray diffractometer. The data are as follows: Figure 1 After ball milling and intercalation, the interlayer spacing of the silicate increases, which prevents the agglomeration of the two-dimensional nanosheets and facilitates the entry of polymer monomers into the interlayer polymerization reaction, resulting in a molecular-level fusion nanocomposite material, which effectively improves the thermal and mechanical properties of the resin.

[0192] The thermal stability of the resin was analyzed by thermogravimetric analysis. The thermogravimetric curves of the residual amount of the boron phenolic resin used in Example 8, Comparative Examples 1 and 2 under nitrogen atmosphere as a function of temperature are shown in FIG. Figure 2 As shown, it can be seen that the carbon residue rate and T of the resin at 800℃ before and after the use of silicone oligomer intercalation 5％ There has been improvement.

[0193] The resin pressed carbon fiber composite materials prepared by Example 8 of the present invention and Comparative Examples 1 and 2 were tested for mechanical properties of the composite materials using a universal testing machine. The data are as follows: Figure 3 As shown. Figure 3 It can be seen that after adding silicone oligomer intercalated montmorillonite modified boron phenolic resin, the flexural strength and interlaminar shear strength of the composite material are significantly improved. The reason is that the introduction of two-dimensional materials can change the direction of the crack, while improving the crack bridging effect, forming a shear band between the thermosetting resin, and thus improving the toughness of the matrix.

[0194] The use of organosilicon oligomer intercalation in the prepared hot-melt boron phenolic resin increases the spacing between the two-dimensional montmorillonite lamellae. This larger interlayer spacing enables in-situ polycondensation of the phenolic resin between the montmorillonite lamellae, resulting in the formation of a montmorillonite exfoliated structure. Furthermore, the montmorillonite lamellae extend the heat transfer pathways, increasing the initial thermal decomposition temperature of the cured resin. The synthesis process of this type of hot-melt boron phenolic resin modified with organosilicon oligomer intercalated montmorillonite is stable and controllable, significantly enhancing the thermal stability and mechanical properties of the modified resin.

[0195] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0196] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a hot-melt boron phenolic resin modified by intercalating montmorillonite with an organosilicon oligomer, characterized in that: The following steps are involved: Ball milling a mixture of an organosilicon oligomer, montmorillonite and water to obtain an organosilicon oligomer intercalated montmorillonite; wherein the organosilicon oligomer is one or more of methyl silicone oil, phenyl silicone oil, amino silicone oil, epoxy silicone oil and polyether modified silicone oil having a molecular weight of 1000-5000 g / mol; The montmorillonite is one or more of organic quaternary ammonium salt intercalated montmorillonite, sodium montmorillonite, calcium montmorillonite and acid activated montmorillonite; The molten phenol and the organosilicon oligomer intercalated montmorillonite are mixed evenly, and then aldehyde is added, the pH is adjusted to 7-8, and the reaction is carried out at 50-70°C for 1-5 hours to obtain an intermediate product; Adding a boric acid derivative to the intermediate product, reacting at 90-120° C. for 0.5-6 hours, adding a modifier after vacuum distillation, stirring evenly, and further vacuum distillation until the gel time of the product at 180±1° C. reaches 120-320 seconds, thereby obtaining an organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin; The molar ratio of phenol, aldehyde and boron compound is 10-200:12-300:1-60; the weight ratio of phenol, organosilicon oligomer intercalated montmorillonite and modifier is 100:1-10:1-30; the aldehyde is one or more of formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, trioxymethylene and paraformaldehyde; Modifiers include polyvinyl acetal, thermoplastic phenolic resin, polyamide, epoxy resin E 20 , epoxy resin E 44 , epoxy resin E 51 Epoxy resin F 44 With epoxy resin F 51 One or more of; One or more of NaOH, NH3·H2O and Ba(OH)2 is used to adjust the pH; The phenol is one or both of monohydric phenol and dihydric phenol; the boron compound is boric acid or a boric acid derivative; The monohydric phenol is one or more of phenol, o-cresol, m-cresol, p-cresol, α-naphthol, β-naphthol and 4-hydroxymethylphenol; the dihydric phenol is one or more of o-catechol, resorcinol, hydroquinone, bisphenol A and bisphenol F; Boric acid derivatives include one or more of p-boric acid, phenylboric acid, hydroxymethylphenylboric acid, hydroxyphenylboric acid, biphenylboric acid, borax, sodium borate, diphenylboric acid, methylphenylboric acid, dimethylphenylboric acid, methoxyphenylboric acid, isopropylphenylboric acid, ethoxyphenylboric acid, 1,4-phenylenediboric acid, ethylphenylboric acid, butylphenylboric acid, 2,4,6-triphenylboroxine and 3-hydroxyphenylboric acid.

2. The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin prepared according to the method of claim 1, characterized in that: The mass ratio of the organosilicon oligomer to the montmorillonite is 1-10:10-1.

3. The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin prepared according to the method of claim 1, characterized in that: The ball milling speed is 100-400 rpm and the time is 10-30 h.

4. The organosilicon oligomer intercalated montmorillonite modified hot-melt boron phenolic resin prepared according to the method of claim 1, characterized in that: Initial decomposition temperature T 5% The temperature is 426-500℃, the residual carbon rate is 72.1-80.0%, the viscosity at 70℃ is 28693-66548mPa·s, and the impact strength is 2.6-3.8KJ·m -2 , the bending strength is 57.2-64.6MPa.

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