High-temperature controllable self-foaming prepolymer containing disiloxane structure as well as preparation and use methods thereof

Abstract

The invention belongs to the field of high polymer material preparation and application, and provides a high-temperature controllable self-foaming prepolymer containing a disiloxane structure and a use method of the prepolymer, and the foam molecular structure contains an aliphatic carboxyl structure, a crosslinkable aromatic structure and a disiloxane structure. Through optimization and strict definition of a foaming process, the outstanding effects of controllable foaming times and uniform and controllable foam holes are realized, the problems of non-uniform distribution, serious foaming agent residue and the like of a traditional foaming agent type high-temperature foaming material are avoided, and the foaming agent type high-temperature foaming material has a relatively good application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer material preparation and application, and relates to a high-temperature controllable self-foaming prepolymer containing a disiloxane structure and a preparation and use method thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the present application and does not necessarily pertain to the prior art that is already known in the field of the application.

[0003] Foam materials, also known as porous materials, are a unique binary composite system composed of a solid matrix and a gas phase filler. Their macroscopic properties mainly depend on key topological parameters such as internal pore structure (e.g. open or closed pores), porosity, pore size distribution, and morphology. Their applications span across building energy saving, transportation, electronic information, biomedical, aerospace, and many other key fields.

[0004] Self-foaming technology directly generates gas through internal chemical reactions, eliminating the need for physical or chemical foaming aids. The core principle is that the matrix molecules release gas during the reaction, forming uniform bubble structures through controlled expansion, ultimately creating a porous or foam structure. Compared to traditional foaming processes, self-foaming technology has significant advantages: simplified production process (eliminating the need for adding foaming agents), and reduced costs (reducing raw material and equipment investment). However, this technology faces two major challenges: first, the design of matrix molecules is difficult, requiring precise control of reaction gas release rate and bubble stability; second, the production process control is complex, including the influence of temperature, pressure, and other parameters on the foaming ratio, making it difficult to accurately predict product consistency.

[0005] A study has disclosed an organic silicon-based self-foaming material based on a benzoxazine structure, which contains silicon-oxygen bonds, benzoxazine groups, and carboxyl groups in its foam molecular structure. Although this patent introduces information such as foaming temperature (190-240°C), pore size after foaming (200-300 μm), expansion ratio (50-300%), and density after foaming (0.4-0.9 g / cm3), the ranges of the above information are too broad and not related to each other, and it is impossible to obtain information on whether the cell size and foaming ratio are controllable and how to achieve controllable foaming. In particular, the photos in Examples 10-13 of this patent show that the foaming material exhibits severe oxidation discoloration (even blackening), which seriously affects the performance and application prospects of the foam material, indicating that the foaming process of this patent still needs to be improved. SUMMARY

[0006] In view of the above prior art, especially the poor controllability of the foaming process and the low foaming ratio of the high-temperature self-foaming material in the prior art, the application provides a high-temperature controllable self-foaming prepolymer containing a disiloxane structure, which contains an aliphatic carboxyl structure, a cross-linkable aromatic structure and a disiloxane structure. The prepolymer utilizes the characteristics of the wide decarboxylation temperature range (200℃-220℃) and the mild decarboxylation process of the aliphatic carboxylic acid structure, realizes the outstanding effects of controllable foaming ratio and uniform controllable cell by optimizing and strictly defining the foaming process, avoids the problems of uneven distribution and serious residual of the foaming agent existing in the traditional foaming agent type high-temperature foaming material, and has good application value.

[0007] Therefore, one object of the application is to provide a high-temperature controllable self-foaming prepolymer containing a disiloxane structure, which can self-foam at high temperature, and the foaming ratio is controlled by temperature, and the pore size and distribution are uniform.

[0008] A second object of the application is to provide a process for realizing controllable foaming ratio and uniform controllable cell using the high-temperature controllable self-foaming prepolymer containing a disiloxane structure. The foaming process provided by the application is simple, has large foaming ratio and controllable cell, and especially avoids the oxidation blackening phenomenon occurring in the foaming process reported in the similar data, and the operation process is safe and convenient. In order to realize the above object, the application adopts the following technical scheme: In a first aspect of the application, a high-temperature controllable self-foaming prepolymer containing a disiloxane structure is provided, which contains an aliphatic carboxyl structure, a cross-linkable aromatic structure and a disiloxane structure in the structure of the prepolymer. The prepolymer monomer is characterized in that the structure is as shown in formula (I):

[0009] Formula (I); Wherein, R` is an aliphatic hydrocarbon group, R`` and R``` are independently selected from an aliphatic hydrocarbon group, an aromatic hydrocarbon group and / or an organosilicon group; R1 is a cross-linkable aromatic structure.

[0010] Preferably, the aliphatic hydrocarbon group is selected from one of C1-C10 alkane or halogenated alkane; More preferably, the aliphatic hydrocarbon group is methylene, propylene or methyl; Preferably, the aromatic hydrocarbon group is selected from one of phenyl, phenethyl, methylphenyl, phenolic phenyl; Preferably, the organosilicon group is selected from one of trialkylsiloxy, trialkoxysilicon, short-chain polysiloxane, dendritic polysiloxane, disiloxane; More preferably, the organosilicon group is selected from short-chain polysiloxane and disiloxane; Further preferably, the short-chain polysiloxane has a chain length of 2-3000; Preferably, R1 is a cross-linkable aromatic structure, which is a structure containing an aromatic group that can be cross-linked, preferably a cross-linkable phenolic structure, a cross-linkable aromatic epoxy structure or a cross-linkable benzoxazine structure.

[0011] Preferably, the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer has a foaming temperature of 200-220°C. Preferably, the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer has an expansion ratio of 240-360% after foaming. The present application further provides a high-temperature controllable self-foaming di-siloxane structure-containing prepolymer composition, which is composed of the following raw materials by weight: 100 parts of the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer, 0-10 parts of catalyst A, 0-400 parts of filler, and 0-200 parts of auxiliary.

[0012] Preferably, the catalyst A is a compound capable of catalyzing the cross-linking reaction of the cross-linkable aromatic structure. More preferably, the catalyst A is a Lewis acid base. Further preferably, the catalyst A is benzene sulfonic acid, acetic acid, hexanediamine or sodium hydroxide. Preferably, the filler is various additives capable of improving the performance of the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer. More preferably, the filler is fumed white carbon black, precipitated white carbon black, carbon black, calcium carbonate, aluminum hydroxide or magnesium hydroxide, and various special treated compounds. Further preferably, the filler is silazane-treated white carbon black. Preferably, the auxiliary is various auxiliaries that do not significantly reduce the performance of the foam material after being added. More preferably, the auxiliary includes various functional components and non-functional components. Further preferably, the auxiliary is a thermal oxygen stabilizer, a flame retardant, a conductive agent, a deep curing agent, a pigment or a plasticizer. Most preferably, the auxiliary is iron red. Preferably, the composition is composed of the following raw materials by weight: 100 parts of the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer, 1-3 parts of catalyst A, 1-30 parts of filler, and 1-10 parts of auxiliary.

[0013] In the second aspect of the present application, a process for realizing controllable foaming ratio and uniform controllable cell is provided, which uses the high-temperature controllable self-foaming di-siloxane structure-containing prepolymer. The high-temperature controllable self-foaming prepolymers with disiloxane structure are heat-treated at a certain fixed temperature in a nitrogen atmosphere tube furnace for 4 hours to obtain foamed materials with uniform cells.

[0014] Preferably, the certain fixed temperature refers to any temperature within 220-240℃, preferably an integer temperature, further selected from 200℃, 210℃ and 220℃.

[0015] It should be noted that in order to realize the high-temperature controllable self-foaming of the prepolymers with disiloxane structure, in particular: to realize the controllable foaming ratio and the controllable uniformity of cells, the present application studies the solvent of the monomer preparation reaction of the prepolymer, preferably, the solvent is a mixed solvent of tetrahydrofurfuryl alcohol and tetrahydrofuran, more preferably, the volume ratio of the two is 1:1-1.5, further preferably, 1:1.

[0016] Compared with the traditional single solvent system (for example: dioxane, tetrahydrofuran), under the mixed solvent system of the present application, the obtained prepolymer structure is appropriate, effectively realizing the controllable foaming ratio and the controllable uniformity of cells, and the cell diameter is significantly increased.

[0017] Advantages of the present application (1) The high-temperature controllable self-foaming prepolymers with disiloxane structure of the present application are innovative applications based on the thermal decarboxylation process of aliphatic carboxyl structure applied to the crosslinking system of aromatic resin containing disiloxane structure. The aliphatic carboxyl structure is different from the aromatic carboxyl structure, which is easy to decarboxylate under heat, has a lower decarboxylation temperature, and has a violent decarboxylation process. Therefore, materials containing aromatic carboxyl structure often begin to rapidly decarboxylate at the same time of heat crosslinking, resulting in the consequence that the foaming degree is difficult to control. The decarboxylation temperature of aliphatic carboxyl structure is higher and the decarboxylation temperature range is wider, and the decarboxylation process is relatively mild. Therefore, the material based on aliphatic carboxyl structure has a significant advantage in the preparation of self-foaming materials. The strict limitation of the R` group in the prepolymer monomer structure formula in the present application as various aliphatic groups clearly defines the selected carboxyl structure as aliphatic carboxyl structure, which can avoid the disadvantage of uncontrollable foaming performance due to the too low decarboxylation temperature when the carboxyl group is connected with the aromatic structure.

[0018] (2) The high-temperature controllable self-foaming prepolymer containing a disiloxane structure of the present application not only strictly defines the disiloxane structure and the cross-linkable aromatic structure in addition to the aliphatic carboxyl group as the core point, but also uses the three in unison to form the basis of the innovation of the present application. Traditional cross-linkable resins and elastomers can all be used as the matrix material of the foaming material. In the present application, in order to improve the stability of the cells, three aromatic structures are selected as the skeleton material to provide the rigidity of the cell wall. However, if only the aliphatic carboxyl structure and the cross-linkable aromatic structure are combined, the cross-linking network is often too hard, the foaming effect is not good, and the volume expansion rate of 358% in the present application cannot be achieved. Therefore, the present application further introduces the disiloxane structure to provide a flexible component in the rigid structure, thereby achieving a foaming effect with a larger expansion rate. The disiloxane structure is selected after multiple tests and is different from the use of polysiloxane in related literature. It is found through multiple tests that when the polysiloxane structure is used, the cells are prone to collapse. Therefore, in the present application, the aliphatic carboxyl structure, the cross-linkable aromatic structure, and the disiloxane structure jointly constitute the main body of the invention and are indispensable, which is the result of innovation after a large number of tests.

[0019] (3) The process method provided by the present application uses the above-mentioned high-temperature controllable self-foaming prepolymer containing a disiloxane structure to achieve controllable foaming multiple and uniform controllable cells, which is different from the use of ordinary ovens in related materials, but uses a nitrogen atmosphere tube furnace. The innovative use of the nitrogen atmosphere tube furnace avoids the oxidation reaction of the foaming material by oxygen during the foaming process, eliminates the oxidation blackening phenomenon of the foam, and achieves unexpected results. The process method is simple, practical, and easy to popularize.

[0020] (4) Compared with patent CN120623423A, the present application achieves controllable foaming and controllable foaming multiple. The specific differences include: ① The foaming pore size changes from 200-300 μm to 300-600 μm in multiple ranges, and the range has a corresponding relationship with the foaming temperature, i.e., controllability. Patent CN120623423A does not have the above-mentioned controllability.

[0021] ② Foaming environment: Patent CN120623423A is foamed in an oven, and the foam is oxidized to become black, while in the present application, the foaming is carried out in an "inert gas atmosphere (nitrogen atmosphere tube furnace)" (i.e., in an inert gas atmosphere protection environment), and the foam is not blackened.

[0022] ③ The foaming multiple changes from 50-300% to 200-400%, with a higher foaming multiple.

[0023] ④ The foaming temperature is reduced from 190-240℃ to 200-220℃. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from the structures shown in these drawings without any creative effort.

[0025] Figure 1 is a Fourier infrared spectrum of the prepolymer prepared in Example 3.

[0026] Figure 2 is a Fourier infrared spectrum of the foam prepared in Example 6.

[0027] Figure 3 is a thermal gravimetric analysis of the pyrolysis gas of the prepolymer prepared in Example 3 during heating.

[0028] Figure 4 is a front view photograph of the foam before foaming in Example 6, after foaming in Example 6, after foaming in Example 7, and after foaming in Example 8.

[0029] Figure 5 is a side view photograph of the foam before foaming in Example 6, after foaming in Example 6, after foaming in Example 7, and after foaming in Example 8.

[0030] Figure 6 is an SEM photograph of the interior of the foam material obtained in Example 8. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0032] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0033] In addition, the technical solutions among the various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0034] Unless otherwise specified, the drugs / reagents used are commercially available.

[0035] A high-temperature controllable self-foaming prepolymer containing a disiloxane structure, the prepolymer structure containing an aliphatic carboxyl structure, a cross-linkable aromatic structure and a disiloxane structure, the prepolymer monomer being characterized by a structure as shown in formula (I):

[0036] Formula (I); In formula (I), R' is an aliphatic hydrocarbon group, R'' and R''' are independently selected from various organic groups, including various aliphatic hydrocarbon groups, aromatic hydrocarbon groups and / or organosilicon groups; R1 is a cross-linkable aromatic structure.

[0037] According to the present application, preferably, the foaming temperature of the high-temperature controllable self-foaming prepolymer containing a disiloxane structure is 200-220°C.

[0038] According to the present application, preferably, the expansion ratio of the high-temperature controllable self-foaming prepolymer containing a disiloxane structure after foaming to the material before foaming is 240-360%.

[0039] According to the present application, preferably, the aliphatic hydrocarbon group is selected from C1-C 10 alkane or halogenated alkane, further preferably methylene, propylene or methyl.

[0040] According to the present application, preferably, the aromatic hydrocarbon group is selected from phenyl, phenylethyl, methylphenyl, phenolic phenyl, further preferably phenyl.

[0041] According to the present application, preferably, the organosilicon group is selected from trialkylsiloxy, trialkoxysilyl, short-chain polysiloxane, dendritic polysiloxane, disiloxane, further preferably short-chain polysiloxane, disiloxane; more preferably, the number of chain nodes of the short-chain polysiloxane is 2-3000.

[0042] According to the present application, preferably, R1 in the prepolymer monomer of the high-temperature controllable self-foaming prepolymer containing a disiloxane structure is a cross-linkable aromatic structure, preferably a cross-linkable phenolic structure, a cross-linkable aromatic epoxy structure or a cross-linkable benzoxazine structure.

[0043] According to the present application, a high-temperature controllable self-foaming prepolymer composition containing a disiloxane structure is also provided, comprising the following components in parts by weight: The above high-temperature controllable self-foaming prepolymer containing a disiloxane structure is 100 parts, the catalyst A is 0-10 parts, the filler is 0-400 parts, and the auxiliary is 0-200 parts.

[0044] According to the present application, preferably, the catalyst A is a compound capable of catalyzing the cross-linking reaction of the cross-linkable aromatic structure, including various types of generalized Lewis acid base; further preferably benzene sulfonic acid, acetic acid, hexamethylene diamine and sodium hydroxide, the use of parts is preferably 0-3 parts.

[0045] Benzene sulfonic acid is an organic compound, molecular formula C6H6O3S, molecular weight of 158.18, colorless needle or flaky crystal, easily soluble in water, easily soluble in ethanol, slightly soluble in benzene, insoluble in diethyl ether, carbon disulfide. Mainly used for the preparation of phenol by alkali fusion, also used for the preparation of resorcinol, etc, often used as catalyst in esterification and dehydration reaction.

[0046] Acetic acid, chemical formula CH3COOH, alias acetic acid, is the simplest organic monovalent weak acid (pKa = 4.75 at room temperature) except formic acid, at room temperature and normal pressure for colorless irritating odor liquid, often represented by symbol HOAc or HAc, is the main component of vinegar.

[0047] Hexamethylenediamine (English: Hexamethylenediamine) is an amine organic compound. It is a kind of diamine, containing a hexane carbon chain skeleton and two end amino functional groups, the nature of colorless solid, with very strong ammonia gas smell, similar to piperidine.

[0048] Sodium hydroxide (sodium hydroxide), also known as caustic soda, caustic soda, fire soda, flaky soda, is an inorganic compound, chemical formula NaOH, relative molecular mass of 39.9970. Sodium hydroxide has strong alkaline, corrosive, can be used as acid neutralizer, complex masking agent, precipitating agent, precipitating masking agent, color developing agent, saponifying agent, peeling agent, detergent, etc., very widely used.

[0049] According to the present application, preferably, the filler is a kind of additive that can improve the performance of the controlled self-foaming material based on the aliphatic carboxyl structure, further preferably fumed silica, precipitated silica, carbon black, calcium carbonate, aluminum hydroxide or / and magnesium hydroxide and various special treated compounds, more preferably silica treated with silazane. The use of parts of the filler is 0-400 parts, preferably 0-30 parts.

[0050] White carbon black is a white powder X-ray amorphous silicic acid and silicate product, mainly refers to the precipitated silica, fumed silica and ultrafine silica gel, also includes powder synthetic aluminum silicate and calcium silicate, etc. White carbon black is a porous material, its composition can be represented by SiO2·nH2O, wherein nH2O is in the form of surface hydroxyl group. Soluble in caustic soda and hydrofluoric acid, insoluble in water, solvent and acid (except hydrofluoric acid). High temperature resistance, non-combustible, odorless, no smell, has good electrical insulation.

[0051] Carbon black, also known as lamp black. Chemical formula C, relative molecular mass 12.011, is the amorphous black solid carbon, has a large surface area, relative density of 1.8-2.1g / cm 3 , sublimation at 3652-3697 ℃, boiling point 4827 ℃, insoluble in water, acid and alkali. Can be prepared by thermal decomposition or incomplete combustion of gaseous hydrocarbons.

[0052] Calcium carbonate is an inorganic compound, chemical formula CaCO3, is the main component of limestone, marble, etc. Calcium carbonate is usually white crystals, odorless, insoluble in water, easy to react with acid to release carbon dioxide. It is one of the common substances on earth, exists in the calcite, calcite, chalk, limestone, marble, loess, etc. Rock, also the main component of some animal bones or shells.

[0053] Aluminum hydroxide is an inorganic substance, chemical formula Al(OH)3, is the hydroxide of aluminum. Aluminum hydroxide can react with acid to generate salt and water and can react with strong base to generate salt and water, so it is an amphoteric hydroxide. Because it also shows a certain acidity, it can also be called alumina (H3AlO3). But actually, when it reacts with alkali, it generates tetrahydroxy aluminate ([Al(OH)4] - ). Therefore, it is usually considered as a hydrated metacolloidal acid (HAlO2·H2O), which is divided into industrial grade and pharmaceutical grade according to use.

[0054] Magnesium hydroxide (English name: Magnesium Hydroxide), inorganic alkali compound, the main component of brucite, chemical formula Mg(OH)2, molecular weight 58.32. Hexagonal system white flaky crystal or powder at room temperature, density about 2.36g / cm 3 , refractive index 1.58, Mohs hardness 2.5, melting point 280 ℃ (vacuum decomposition). Almost insoluble in water, slightly alkaline in water, aqueous slurry pH value is 9.5~10.5, insoluble in alcohol, soluble in dilute acid and ammonium salt solution. Magnesium hydroxide has thermal instability, heated to 350 ℃ decomposition into magnesium oxide and water, with dilute acid to generate the corresponding acid magnesium salt and water, with salt or acidic oxide can react, such as with excess ammonium chloride (NH4)2MgCl4 and dissolved, with carbon dioxide to generate magnesium carbonate precipitation, etc.

[0055] According to the application, preferably, the adjuvant is various adjuvants that do not significantly reduce the performance of the foam material after being added, including various functional components and non-functional components, further preferably thermal oxygen stabilizer, flame retardant, conductive agent, deep curing agent, pigment or / and plasticizer; further preferably iron red, the use of parts is preferably 0-10 parts.

[0056] According to the application, preferably, the high-temperature controllable self-foaming prepolymer composition containing a disiloxane structure comprises the following components by mass fraction: The high-temperature controllable self-foaming prepolymer containing a disiloxane structure described above is 100 parts, the catalyst A is 1-3 parts, the filler is 1-30 parts, and the auxiliary agent is 1-10 parts.

[0057] The application provides a process method for realizing controllable foaming multiple and controllable uniform cell of the high-temperature controllable self-foaming prepolymer containing a disiloxane structure, comprising the following steps: The high-temperature controllable self-foaming prepolymer containing a disiloxane structure described above is heat treated at a certain fixed temperature for 4 hours in a nitrogen atmosphere tube furnace to obtain a foam material with uniform cells.

[0058] Preferably, the certain fixed temperature refers to any temperature within 220-240 DEG C, preferably an integer temperature, and further selected from 200 DEG C, 210 DEG C and 220 DEG C.

[0059] It should be noted that in order to realize the high-temperature controllable self-foaming of the prepolymer containing a disiloxane structure, especially: realize controllable foaming multiple and controllable uniform cell, the application studies the solvent of the monomer preparation reaction of the prepolymer, preferably, the solvent is a mixed solvent of tetrahydrofurfuryl alcohol and tetrahydrofuran, more preferably, the volume ratio of the two is 1:1-1.5, and further preferably, 1:1.

[0060] Compared with the traditional single solvent system (for example: dioxane, tetrahydrofuran), under the mixed solvent system of the application, the obtained prepolymer structure is appropriate, and the foaming multiple and the uniform cell are effectively realized, and the cell diameter is significantly increased.

[0061] According to the application, the polymer containing at least the structural unit shown in formula (I) in the molecular structure is also provided as the use of the high-temperature self-foaming foam material.

[0062] Compared with the patent CN120623423A, the application realizes controllable foaming, and the foaming multiple has controllability. The specific differences include: ① The foaming pore diameter changes from 200-300 μm to 300-600 μm in multiple ranges, and the range has a corresponding relationship with the foaming temperature, that is, controllability. The patent CN120623423A does not have the controllability.

[0063] ② Foaming environment: the patent CN120623423A is foamed in an oven, and the foam is black, indicating oxidation, while in the application, the foaming is carried out in an inert atmosphere (nitrogen atmosphere tube furnace) (that is, in an inert atmosphere protection environment), and the foam is not black.

[0064] 3. Foaming ratio changes from 50-300% to 200-400%, with a higher foaming ratio.

[0065] 4. Foaming temperature reduces from 190-240℃ to 200-220℃.

[0066] Principle of the present application: The high-temperature controllable self-foaming prepolymer containing disiloxane structure of the present application can effectively integrate the advantages of mild decomposition of aliphatic carboxyl structure to release gas at high temperature, high hardness of crosslinked aromatic structure, and good flexibility of disiloxane structure, and the prepared foaming material has the advantages of wide foaming temperature range, appropriate foaming speed, strong bubble wall rigidity, and uniform cell, thereby realizing the innovative effect of controllable foaming. Although there are a large number of reports on silicone-modified phenolic resins in related literature, there is no research on the application of this system to self-foaming material system, and the present application has significant innovation in molecular structure design.

[0067] The present application will be further described in detail below in conjunction with specific examples, it should be pointed out that the specific examples are an explanation of the present application rather than a limitation.

[0068] Example 1 Weigh the measured amount of N 1 , N 1 '-(1,1,3,3-tetramethyldisiloxane-1,3-diyl) bis(propane-3,1-dialkyl) bis(propane-1,3-diamine) (CAS No. 3029142-09-1) (15.82 g) and formaldehyde aqueous solution (4.05 g) and tetrahydrofurfuryl alcohol + tetrahydrofuran (1:1) (300 ml) into a three-necked flask, stir at room temperature for 2 h, then weigh the acid-catalyzed phenolic prepolymer (5.00 g, s trade name: Novolacs) and 4,4-bis(4-hydroxyphenyl) valeric acid (14.3 g) are dissolved in tetrahydrofuran, and refluxed for 8 h. After the reaction is completed, the solvent is removed by rotary evaporator, further purified, and then dried in a vacuum drying oven to obtain a phenolic resin high-temperature controllable self-foaming prepolymer containing disiloxane structure.

[0069] Example 2 Weigh the measured amount of N 1 , N 1'-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-dialkyl)bis(propane-1,3-diamine) (CAS No. 3029142-09-1) (15.82 g) was added to a three-necked flask along with bisphenol A type epoxy resin prepolymer (6.00 g, molecular weight 3800), 4,4-bis(4-hydroxyphenyl)valeric acid (14.3 g), and tetrahydrofuran (300 ml). The mixture was reacted at reflux temperature for 6 h. After the reaction was complete, the solvent was removed by rotary evaporation and further purified. The purified product was then dried in a vacuum drying oven to obtain a high-temperature controllable self-foaming aromatic epoxy resin prepolymer containing a disiloxane structure.

[0070] Example 3 Weigh N 1 N 1 '-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(propane-3,1-dialkyl)bis(propane-1,3-diamine) (CAS No. 3029142-09-1) (25.1 g), 37% formaldehyde aqueous solution (20.4 g), and tetrahydrofurfuryl alcohol + tetrahydrofuran (1:1) (400 mL) were mixed thoroughly in a three-necked flask. 4,4-bis(4-hydroxyphenyl)valeric acid (17.16 g) was dissolved in 100 mL of tetrahydrofuran and added dropwise to the above mixture. The mixture was refluxed for 6 h. After the reaction was complete, the solvent was removed using a rotary evaporator, and the mixture was further purified and dried to obtain the prepolymer monomer. The obtained prepolymer monomer was then placed in a mold and cured in a nitrogen-atmosphere tube furnace using a staged temperature increase curing method. The specific temperature increase program was: 115℃ / 1 h, 125℃ / 3 h, 135℃ / 1 h. A high-temperature controllable self-foaming prepolymer containing a disiloxane structure, derived from benzoxazine resins, was obtained. The infrared spectrum is shown below. Figure 1 As shown.

[0071] Example 4 The phenolic resin prepolymer with a disiloxane structure that is capable of high-temperature controllable self-foaming obtained in Example 1 was heated at 220°C for 4 hours in a tube furnace under nitrogen atmosphere to obtain foam material.

[0072] Example 5 The prepolymer containing a disiloxane structure and high-temperature controllable self-foaming aromatic epoxy resin obtained in Example 2 was heated at 210°C for 4 hours in a tube furnace under nitrogen atmosphere to obtain foam material.

[0073] Example 6 The benzoxazine resin-based high-temperature controllable self-foaming prepolymer containing a disiloxane structure obtained in Example 3 was heated at 200°C for 4 hours in a nitrogen atmosphere tube furnace to obtain a foam material. The infrared spectrum of the foam material is shown below. Figure 2 As shown.

[0074] Example 7 The prepolymer obtained in Example 3 was heated at 210℃ for 4h in a tube furnace under nitrogen atmosphere to obtain a foamed material.

[0075] Example 8 The prepolymer obtained in Example 3 was heated at 220℃ for 4h in a tube furnace under nitrogen atmosphere to obtain a foamed material.

[0076] Test Example 1 The size and cell diameter of the foamed precursor before and after foaming in Examples 6, 7 and 8 were measured (the test method for foaming volume was drainage method, and the test method for cell diameter was scanning electron microscopy random sampling test points, counting the cell diameter in the image, and taking the average of 4 times of shooting for each sample), as shown in Figures 4-5 The test data are listed in Table 1.

[0077] Test Example 2 The foamed material obtained in Example 8 was analyzed by scanning electron microscopy, and the cell structure thereof is shown in Figure 6 The test data are listed in Table 1.

[0078] Test Example 3 The thermal gravimetric pyrolysis gas infrared spectrum analysis chart of the siloxane-based self-foaming material monomer prepared in Example 3 is shown in Figure 3 As can be seen from Figure 3 , the pyrolysis gas is mainly carbon dioxide.

[0079] Table 1 Properties of silicone self-foaming materials and comparative examples

[0080] As can be seen from the data in Table 1, by optimizing and strictly defining the foaming process (especially strictly defining the foaming environment of the nitrogen atmosphere tube furnace), the foaming ratio is controllable (different expansion ratios of 240% to 360% corresponding to different foaming temperatures), and the cell uniformity is controllable (not only uniform cell, but also different cell diameters of 300-600μm corresponding to different foaming temperatures). The controllability of the foaming ratio has not been reported in related materials, indicating that unexpected effects have been achieved.

[0081] Comparative Example 1 (CN115894927A) discloses a foamed silicone gel thermal insulation material and a preparation method. The invention uses azobisisobutyronitrile as a chemical foaming agent to prepare a silicone foam material with a density of 0.59g / cm -2 . The method is complex in process, has many types of raw materials, and is difficult to manage in production. At the same time, azo foaming agents and the gases produced by their pyrolysis will poison the silicone gel and make it unable to cure, so additional catalysts need to be added, increasing the production cost.

[0082] Comparative Example 2 (CN118685044A) adopts a supercritical fluid physical foaming method to obtain a silicone rubber foamed material with a cell size of 70 μm. The vulcanization temperature of the foamed material prepared by this method reaches 180℃, and the pressure reaches 7 MPa. Compared with the physical foaming method described in the literature, the foaming process adopted by the present application does not need to use a supercritical fluid foaming device, and the foamed material can be prepared without a complex foaming process, which reduces the production process flow, effectively reduces the production cost, and improves the production efficiency.

[0083] By comparing the similar literatures at home and abroad, it can be seen that the present application can more easily realize the effect of controllable foaming degree by changing the foaming temperature, and the foaming volume can be 220%-320%. The foaming process is not only simple than the comparative file but also has a much higher foaming ratio. Further, the aliphatic carboxyl-based disiloxane self-foaming material of the present application can further regulate the foaming volume by adjusting the content of carboxyl and the foaming temperature to meet the technical requirements under different conditions, which has significant advantages.

[0084] Meanwhile, compared with patent CN120623423A, the present application realizes controllable foaming, and the foaming ratio is controllable. The specific differences include: ① The foaming pore size changes from 200-300 μm to 300-600 μm in multiple ranges, and the range has a corresponding relationship with the foaming temperature, that is, controllable. Patent CN120623423A does not have the above controllability.

[0085] ② Foaming environment, patent CN120623423A is foamed in an oven, and the foam is black, indicating oxidation, while the present application is foamed in an inert atmosphere (nitrogen atmosphere tube furnace) (that is, in an inert atmosphere protection environment), and the foam is not black.

[0086] ③ The foaming ratio changes from 50-300% to 200-400%, with a higher foaming ratio.

[0087] ④ The foaming temperature is reduced from 190-240℃ to 200-220℃.

[0088] It should be noted that compared with the traditional single solvent system (for example: dioxane, tetrahydrofuran), the pre-polymer structure obtained by using the mixed solvent system of the present application is appropriate, which effectively realizes the controllable foaming ratio, uniform controllable cell, and significantly increased cell diameter.

[0089] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A high-temperature controllable self-foaming prepolymer containing a disiloxane structure, wherein the prepolymer structure contains an aliphatic carboxyl group structure, a crosslinkable aromatic structure, and a disiloxane structure, and the prepolymer monomer of the prepolymer is characterized by having a structure as shown in formula (I): Formula (I); wherein R` is an aliphatic group, and R`` and R``` are independently selected from aliphatic hydrocarbon groups, aromatic hydrocarbon groups and / or organosilicon groups, respectively; R1 is a crosslinkable aromatic structure.

2. The high temperature controllably expanding disiloxane material of claim 1, wherein, The aliphatic hydrocarbon group is selected from one of C1-C10 alkanes or haloalkanes; Alternatively, the aliphatic hydrocarbon group may be methylene, propylene, or methyl; Alternatively, the aromatic hydrocarbon group is selected from one of phenyl, phenethyl, methylphenyl, and phenolic phenyl; Alternatively, the organosilicon group is selected from one of trialkylsiloxy, trialkoxysilyl, short-chain polysiloxane, dendritic polysiloxane, and disiloxane; Alternatively, the organosilicon group is selected from short-chain polysiloxanes and disiloxanes; Alternatively, the number of chain segments of the short-chain polysiloxane is 2-3000; Alternatively, R1 can be a crosslinkable phenolic structure, a crosslinkable aromatic epoxy structure, or a crosslinkable benzoxazine structure.

3. The high temperature controllably expanding disiloxane material of claim 1, wherein, The foaming temperature of the high-temperature controllable self-foaming disiloxane material is 200-220℃; Alternatively, the expansion ratio of the high-temperature controllable self-foaming disiloxane material after foaming to that before foaming is 240-360%.

4. A high temperature controllably self-foaming disiloxane-containing prepolymer composition consisting of the following parts by weight of raw materials: The above-mentioned high-temperature controllable self-foaming prepolymer containing a disiloxane structure consists of 100 parts, catalyst A 0-10 parts, filler 0-400 parts, and additives 0-200 parts.

5. The high temperature controlled self-foaming disiloxane-containing pre- polymer composition of claim 4, wherein, Catalyst A is a compound capable of catalyzing the cross-linking reaction of cross-linkable aromatic structures; Alternatively, catalyst A may be a Lewis acid or base; Alternatively, catalyst A may be benzenesulfonic acid, acetic acid, hexamethylenediamine, or sodium hydroxide.

6. The high temperature controlled self-foaming disiloxane-containing pre- polymer composition of claim 4, wherein, The filler is a variety of additives that can improve the performance of controllable self-foaming materials with aliphatic carboxyl groups and disiloxanes. Alternatively, the filler may be fumed silica, precipitated silica, carbon black, calcium carbonate, aluminum hydroxide and / or magnesium hydroxide, and various specially treated compounds thereof; Alternatively, the filler may be silica treated with silazane.

7. The high temperature controlled self-foaming disiloxane-containing pre- polymer composition of claim 4, wherein, The additives mentioned are various additives that do not significantly reduce the performance of the foam material after being added; Alternatively, the additives may include various functional and non-functional components; Alternatively, the additives may be thermo-oxidative stabilizers, flame retardants, conductive agents, deep curing agents, pigments, and / or plasticizers; Alternatively, the additive may be iron oxide red.

8. The high temperature controlled self-foaming disiloxane-containing pre- polymer composition of claim 4, wherein, It is composed of the following raw materials in parts by weight: 100 parts of the high-temperature controllable self-foaming prepolymer composition containing a disiloxane structure as described in any one of claims 1-4, 1-3 parts of catalyst A, 1-30 parts of filler, and 1-10 parts of additives.

9. A process method for achieving controllable expansion ratio and controllable cell uniformity using the high-temperature controllable self-foaming prepolymer containing a disiloxane structure as described in any one of claims 1-4, comprising: A prepolymer containing a disiloxane structure that can be controlled to foam at high temperature is heat-treated in a tube furnace under nitrogen atmosphere at a fixed temperature for 4 hours to obtain a foam material with uniform cell structure.

10. The process for achieving controllable foaming ratio and controllable uniform cell size of the high temperature controllable self-foaming disiloxane containing prepolymers of claim 9, wherein, The certain fixed temperature is any temperature within the range of 220-240°C, preferably an integer temperature, further selected from 200°C, 210°C and 220°C. The certain fixed temperature is any temperature within the range of 220-240°C, preferably an integer temperature, further selected from 200°C, 210°C and 220°C. The certain fixed temperature is any

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