Carbon dioxide-based block polyether self-supply hydrogen foaming modified liquid silica gel foam and preparation method thereof

Abstract

The present application belongs to the technical field of organic silicon foamed material, and particularly relates to a carbon dioxide based block polyether self-supply hydrogen foaming modified liquid silica gel foam and a preparation method thereof, raw material composition of which comprises vinyl polysiloxane, hydrogen-containing silicone oil and platinum catalyst, and the composition further comprises a hydroxyl-terminated polycarbonate-polyether block copolymer prepared by copolymerization of carbon dioxide and alkylene oxide; the molecular chain of the block copolymer comprises a block structure formed by polycarbonate hard segments and polyether soft segments, and each end of the molecular chain has one hydroxyl group. The carbon dioxide based block polyether self-supply hydrogen foaming modified liquid silica gel foam and the preparation method thereof solve the defects of uneven foaming, poor hydrolysis resistance, low-temperature brittleness, great production safety hazard and high carbon raw material of the existing foaming silica gel foam with additional small molecule hydrogen source.

Description

Technical Field

[0001] This invention relates to the technical field of organosilicon foam materials, specifically to carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam and its preparation method. Background Technology

[0002] Addition-type liquid silicone foam is an elastic foam material that uses vinyl polysiloxane as a matrix and achieves cross-linking and curing through a hydrosilylation reaction under the action of a platinum catalyst. Its foaming principle typically relies on the addition of small molecule compounds containing active hydrogen (such as deionized water, methanol, ethylene glycol, glycerol, etc.), which, under platinum catalysis, undergo a hydrosilylation and dehydrogenation reaction with the Si-H bonds in the hydrogen-containing silicone oil, releasing hydrogen gas and forming a cell structure during the cross-linking process of the silicone rubber, ultimately obtaining porous foam products. This type of material is widely used in electronic cushioning, automotive sealing, and industrial vibration damping due to its wide temperature range (-50℃ to +200℃), ozone aging resistance, and excellent electrical insulation.

[0003] However, existing foaming technologies using external small-molecule hydrogen sources have the following systemic drawbacks: Adding small-molecule alcohols (such as ethylene glycol, with a molecular weight of only 62 g / mol) results in a significant difference in polarity between the two, while the vinyl silicon matrix is ​​a non-polar organosilicon material. During room-temperature mixing, small-molecule alcohols are difficult to achieve uniform molecular-level dispersion within the silicon matrix, easily forming localized agglomerates or microdroplets. During the foaming stage, these agglomerated regions exhibit excessively high concentrations of active hydrogen, leading to a much higher gas production rate than the surrounding areas. This results in non-uniform bubble nucleation and abnormal growth, causing defects such as a mixture of large and small pores and continuous bubble breakage. In actual production, the coefficient of variation for cell size in traditional formulations using ethylene glycol for foaming typically exceeds 30%, making it difficult to maintain a yield rate consistently above 85%.

[0004] In the hydrosilylation reaction, only a portion of the added small-molecule alcohols and water participate in the dehydrogenation reaction, leaving unreacted free alcohols and water in the cross-linked network. During long-term service of the foam, these small molecules slowly migrate and seep out, leaving behind micro-defects that become stress concentration points. Furthermore, free water catalyzes the hydrolysis of the polysiloxane backbone, accelerating the degradation of the silicon chains under humid and hot conditions, leading to a decline in the mechanical properties of the foam. In addition, pure silicone foam lacks a rigid reinforcing structure, resulting in inherent deficiencies in abrasion resistance and tear resistance. At low temperatures, the silicone rubber chain segments freeze, causing a sharp decrease in bending toughness and making it prone to brittle fracture.

[0005] Small molecule alcohol foaming agents (such as methanol, ethanol, and ethylene glycol) have low flash points (methanol flash point is only 11℃, and ethanol flash point is 13℃) and high volatility. They easily volatilize and accumulate during processes such as batching, mixing, and high-temperature molding, forming flammable vapor mixtures that pose a fire and explosion risk. Meanwhile, traditional formulations use petroleum-based monomers such as propylene oxide and ethylene oxide as raw materials for polyether polyols, resulting in high carbon emissions during production and a large carbon footprint for the products. This leads to market access barriers under green supply chain requirements. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing carbon dioxide-based block polyether self-hydrogenated modified liquid silicone foam and its preparation method. It solves the defects of existing silicone foams with added small molecule hydrogen sources, such as uneven cell structure, poor hydrolysis resistance, low-temperature brittleness, significant production safety hazards, and high carbon content in raw materials.

[0007] To solve the above-mentioned technical problems, the objective of this invention is achieved through the following technical solution: Carbon dioxide-based block polyether self-hydrogenated foaming modified liquid silicone foam has a raw material composition including vinyl polysiloxane, hydrogen-containing silicone oil and platinum catalyst. The composition also contains hydroxyl-terminated polycarbonate-polyether block copolymer obtained by copolymerizing carbon dioxide and epoxy alkane. The molecular chain of the block copolymer is composed of polycarbonate hard segments and polyether soft segments forming a block structure, with a hydroxyl group at each end of the molecular chain; The terminal hydroxyl groups undergo a dehydrogenation condensation reaction with the Si-H bonds in the hydrogen-containing silicone oil to release hydrogen gas, which serves as the gas source for foaming the composition. The polycarbonate hard segments form physical entanglements and hydrogen bond interactions in the silicone rubber crosslinking network, constituting a reinforcing structure; The polyether soft segments provide the ability for compliant molecular chain movement at low temperatures.

[0008] As a further improvement of the present invention, the copolymer has a number-average molecular weight of 2000-8000 g / mol, carbon dioxide structural units account for more than 30% of the total mass of the copolymer, and a hydroxyl value of 40 mg KOH / g-72 mg KOH / g. In the block copolymer, carbonate segments formed by alternating copolymerization of carbon dioxide and propylene oxide constitute polycarbonate hard segments, and homopolymer segments of propylene oxide or ethylene oxide constitute polyether soft segments.

[0009] As a further improvement of the present invention, the raw material composition of the composition, by weight, includes: 60-90 parts of vinyl polysiloxane; 5-35 parts of the block copolymer; 3-12 parts of hydrogen-containing silicone oil; 0.001-0.05 parts of platinum-based catalyst; and 0-25 parts of inorganic filler.

[0010] As a further improvement of the present invention, the block copolymers are divided into three grades according to the hydroxyl value range: the block copolymers with a hydroxyl value of 40-48 mgKOH / g are used to prepare a density of 0.15-0.25 g / cm³. 3 Slow-rebound open-cell foam; the block copolymer with a hydroxyl value of 58–63 mg KOH / g is used to prepare a density of 0.25–0.40 g / cm³. 3 A general-purpose cushioning foam; the block copolymer with a hydroxyl value of 67–72 mgKOH / g is used to prepare a density of 0.40–0.60 g / cm³. 3 High-support foam.

[0011] As a further improvement of the present invention, the vinyl polysiloxane is α,ω-divinyl polydimethylsiloxane, with a vinyl content of 0.1mol% to 1.5mol%; the hydrogen-containing silicone oil is a side-hydrogen type polyorganosiloxane, with an active hydrogen content of 0.5wt% to 1.6wt%; and the platinum-based catalyst is a chloroplatinic acid-vinylsiloxane complex.

[0012] As a further improvement of the present invention, the inorganic filler is selected from one or more of fumed silica, light calcium carbonate, and aluminum hydroxide; the specific surface area of ​​the fumed silica is 150 m². 2 / g~300m 2 / g, wherein the median particle size of the aluminum hydroxide is 1μm to 5μm.

[0013] This invention also provides a method for preparing carbon dioxide-based block polyether self-hydrogen-donating modified liquid silicone foam, comprising the following steps: The vinyl polysiloxane is mixed with the block copolymer to form a homogeneous mixture, thereby dispersing the block copolymer at the molecular level in the matrix; Hydrogen-containing silicone oil and platinum-based catalyst are added to the mixture and mixed thoroughly. The obtained composition is injected into a mold and kept at 60℃~130℃ for 10min~60min to allow the hydrosilylation crosslinking reaction and the terminal hydroxyl dehydrogenation gas generation reaction to proceed simultaneously. Hydrogen gas is uniformly nucleated and foamed in the crosslinking network and then solidified.

[0014] As a further improvement of the present invention, the material temperature is controlled below 35°C during the mixing process; the mold cavity filling rate is 60% to 95%; and the curing temperature is positively correlated with the hydroxyl value of the block polyether.

[0015] Specifically, the preparation method of the present invention includes: S1 Premixing: At room temperature (20-30℃), the vinyl liquid silicone matrix and inorganic reinforcing filler are added to a planetary or twin-shaft stirred tank and stirred at a low speed of 50-200 rpm for 20-40 min until the filler is completely wetted and uniformly dispersed, eliminating agglomerates. Then, CO2-based hydroxyl-terminated polycarbonate-polyether block copolymer is added, and the stirring speed is increased to 200-500 rpm for 15-30 min to ensure the block polyether is fully dissolved and dispersed in the silicone matrix, resulting in a silicone-based premix with a uniform appearance and no visible phase separation. The high molecular weight properties of the block polyether in this step enable it to form a thermodynamically stable homogeneous solution system in the silicone matrix, laying the foundation for subsequent uniform gas production.

[0016] S2 Catalytic Compounding: Hydrogen-containing silicone oil and platinum-based catalyst are added sequentially to the premix. The stirring speed is increased to 800–1500 r / min, and the mixture is stirred at high speed for 5–15 min to ensure rapid and uniform mixing of all components. During stirring, the material temperature must be controlled to not exceed 35℃ to prevent premature reaction of the platinum catalyst, which could lead to an increase in the viscosity of the liquid. This step yields a homogeneous, foamable mixture with a suitable operating window (typically 30–90 min at room temperature), facilitating subsequent molding operations.

[0017] S3 Molding and Curing: The mixture is injected into a preheated, sealed steel mold. The mold cavity filling volume is 60%–95%, with the specific ratio adjusted according to the hydroxyl value of the block polyether and the target foam density: higher filling volume for low hydroxyl value formulations (85%–95%) and lower filling volume for high hydroxyl value formulations (60%–80%). The mold cavity uses pre-set microporous channels for micro-venting to prevent pressure buildup and abnormally large bubbles. The curing temperature is 60–130℃, with constant-temperature foaming and curing for 10–60 minutes. During this process, the hydrosilylation crosslinking reaction and the dehydrogenation gas generation reaction occur simultaneously. Hydrogen gas uniformly nucleates, grows, and stabilizes within the crosslinked silicone rubber network. After demolding, the mixture is allowed to cure naturally at room temperature for 24 hours to allow the residual crosslinking reaction to complete and internal stress to be released, ultimately yielding the finished foamed silicone foam.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam and its preparation method. This invention proposes a high-molecular-weight hydroxyl-terminated in-situ hydrogen-supplying foaming mechanism. The CO2-based hydroxyl-terminated polycarbonate-polyether block copolymer is a high-molecular-weight polymer with a hydroxyl group at each end of its molecular chain. Under the action of a platinum catalyst, the terminal hydroxyl groups undergo a hydrosilylation dehydrogenation reaction with the Si-H bonds in the hydrogen-containing silicone oil, releasing one mole of H2 per mole of terminal hydroxyl group. The terminal hydroxyl groups are chemically anchored at the polymer chain end, and their dispersion state in the silicone matrix is ​​determined by the molecular-level solubility characteristics of the polymer. The foaming active sites are uniformly distributed throughout the entire formulation system. The hydrogen release process is mild and controllable, occurring synchronously in all regions, fundamentally eliminating local over-foaming and foam breakage defects. The measured coefficient of variation of cell size is reduced from over 30% in traditional formulations to less than 10%.

[0019] 2. This invention utilizes the polycarbonate hard segments (formed by alternating copolymerization of CO2 and epoxy alkane) in the CO2-based block copolymer molecular chain to form physical entanglement and hydrogen bonding interactions within the silicone rubber crosslinking network, providing rigid reinforcement to the flexible siloxane network. Measured tear strength is increased by 30%–107% compared to traditional formulations, and compression set is reduced by 40%–70%. Simultaneously, the polyether soft segments impart excellent low-temperature flexibility to the molecular chain; it exhibits no brittleness or whitening after bending 180° at an extreme low temperature of -35°C, completely solving the problem of low-temperature brittleness and fracture in traditional silicone foam.

[0020] 3. This invention uses a CO2-based block copolymer with propylene carbonate as the dispersion solvent to replace the low-flash-point, volatile small-molecule alcohol blowing agent. The finished product has a flash point of not less than 130°C, and the volatilization rate is extremely low during processes such as batching and high-temperature molding, significantly reducing the risk of fire and explosion. There are no free small molecules remaining in the formulation, eliminating the long-term defect source of small molecule migration and hydrolysis of the siloxane backbone. The overall production cycle is shortened by 15% to 30% compared to traditional processes.

[0021] 4. The CO2-based block copolymer used in this invention uses industrial waste gas CO2 as a comonomer. During the polymerization reaction, CO2 is chemically bonded and fixed into the polymer molecular chain, forming stable carbonate segments. Based on a CO2 structural unit content of not less than 30 wt% in the polymer, the amount of CO2 fixed in one kilogram of foam product is 80–180 g. This low-carbon attribute provides the product with a basis for low-carbon certification and aligns with green supply chain access requirements. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0023] The performance metrics tests in the embodiments were conducted according to the following standards: Tear strength: GB / T 529; Compression set: GB / T 7759; Open area: GB / T 10799; Apparent density: GB / T 533; Low temperature bending: GB / T 1845 or similar standard.

[0024] Example 1 This embodiment provides a low hydroxyl value slow rebound open-cell foam. 75 parts by weight of α,ω-divinyl polydimethylsiloxane (vinyl content 0.8 mol%, viscosity 10000 mPa·s at 25℃) and 8.0 parts by weight of fumed silica (specific surface area 200 m²) were mixed. 2 Add 18 parts by weight of CO2-based hydroxyl-terminated polycarbonate-polyether block copolymer (hydroxyl value 44 mg KOH / g, CO2 structural unit mass percentage 35%) to a planetary mixer and stir at 120 rpm for 30 min until the silica is completely wetted and dispersed. Add 6.0 parts by weight of side-hydrogenated silicone oil (active hydrogen content 0.8 wt%) and 0.008 parts by weight of Karstedt catalyst (platinum content 6000 ppm) to the premix and stir at 1000 rpm for 8 min, controlling the material temperature not to exceed 32℃. Pour the mixture into a preheated 85℃ sealed steel mold with a cavity filling rate of 90%. After curing at a constant temperature for 35 min, demold and allow to mature naturally at room temperature for 24 h to obtain the finished foam.

[0025] Example 2 This embodiment provides a general-purpose cushioning foam with a medium hydroxyl value.

[0026] 70 parts by weight of α,ω-divinyl polydimethylsiloxane (vinyl content 0.8 mol%, viscosity 10000 mPa·s at 25℃) and 12.0 parts by weight of light calcium carbonate (particle size 800 mesh) were added to a planetary stirred tank and stirred at 100 r / min for 28 min until the calcium carbonate was completely wetted and dispersed. 22 parts by weight of CO2-based hydroxyl-terminated polycarbonate-polyether block copolymer (hydroxyl value 61 mg KOH / g, CO2 structural unit mass percentage 38%) were added and stirred at 300 r / min for 20 min to obtain a homogeneous silicone-based premix. 7.5 parts by weight of side-hydrogenated silicone oil (active hydrogen content 1.0 wt%) and 0.010 parts by weight of Karstedt catalyst (platinum content 6000 ppm) were added sequentially to the premix and stirred at 1000 r / min for 10 min, controlling the material temperature to not exceed 33℃. The mixture is injected into a sealed steel mold preheated to 90°C, with a mold cavity filling rate of 85%. After curing at a constant temperature for 30 minutes, the mixture is demolded and allowed to mature naturally at room temperature for 24 hours to obtain the finished foam.

[0027] Example 3 This embodiment provides a high hydroxyl value wear-resistant and corrosion-resistant foam.

[0028] 65 parts by weight of α,ω-divinyl polydimethylsiloxane (vinyl content 1.0 mol%, viscosity 15000 mPa·s at 25℃) and 20.0 parts by weight of aluminum hydroxide (particle size D) were mixed. 50 =3μm) was added to a planetary stirred tank and stirred at a low speed of 80 rpm for 35 min until aluminum hydroxide was completely wetted and dispersed. 28 parts by weight of CO2-based hydroxyl-terminated polycarbonate-polyether block copolymer (hydroxyl value 69 mg KOH / g, CO2 structural unit mass percentage 40%) was added and stirred at a medium speed of 250 rpm for 25 min to obtain a homogeneous silicone-based premix. 9.0 parts by weight of side-hydrogenated silicone oil (active hydrogen content 1.2 wt%) and 0.012 parts by weight of Karstedt catalyst (platinum content 6000 ppm) were added to the premix sequentially and stirred at a high speed of 1200 rpm for 6 min, controlling the material temperature not to exceed 30℃. The mixture was poured into a sealed steel mold preheated to 105℃, with a mold cavity filling rate of 72%. After curing at a constant temperature for 22 min, the mixture was demolded and allowed to mature naturally at room temperature for 24 h to obtain the finished foam.

[0029] Comparative Example 1 This comparative example provides a conventional ethylene glycol foam.

[0030] 75 parts by weight of α,ω-divinyl polydimethylsiloxane (same as in Example 1) and 8.0 parts by weight of fumed silica were added to a planetary stirred tank and stirred at a low speed of 120 rpm for 30 min until the silica was dispersed. 18 parts by weight of ethylene glycol (analytical grade) were added and stirred at a medium speed of 350 rpm for 20 min. It was observed that ethylene glycol had poor dispersion in the silicon matrix, and localized turbidity appeared in the solution. 6.0 parts by weight of hydrogen-containing silicone oil and 0.008 parts by weight of Karstedt catalyst were added sequentially and stirred at a high speed of 1000 rpm for 8 min. The mixture was poured into a sealed steel mold preheated to 85°C, with a mold cavity filling rate of 85%. After curing at a constant temperature for 35 min, the mixture was demolded and allowed to mature at room temperature for 24 h.

[0031] Comparative Example 2 This comparative example provides a small molecule alcohol foam that does not contain CO2-based block polyether.

[0032] 70 parts by weight of α,ω-divinyl polydimethylsiloxane and 12.0 parts by weight of light calcium carbonate were added to a planetary stirred tank and stirred at low speed until the calcium carbonate was dispersed. 18 parts by weight of ethylene glycol (corresponding to the hydroxyl equivalent of the block copolymer in Example 2) were added and mixed at medium speed. 7.5 parts by weight of hydrogen-containing silicone oil and 0.010 parts by weight of Karstedt catalyst were added sequentially and stirred at high speed until homogeneous. The mixture was poured into a sealed steel mold preheated to 90°C, with a mold cavity filling rate of 85%. After curing at a constant temperature for 30 minutes, the mold was demolded and allowed to mature at room temperature for 24 hours.

[0033] Comparative Example 3 This comparative example provides a small molecule alcohol foam that does not contain carbonate segments.

[0034] 70 parts by weight of α,ω-divinyl polydimethylsiloxane and 12.0 parts by weight of light calcium carbonate were added to a planetary stirred tank and stirred at low speed until the calcium carbonate was dispersed. 18 parts by weight of a common polyether polyol (non-CO2 copolymer type, hydroxyl value 56 mgKOH / g, close to the molecular weight and hydroxyl value of the CO2-based block polyether in Example 2) were added and mixed at medium speed. 7.5 parts by weight of side-hydrogenated silicone oil and 0.010 parts by weight of Karstedt catalyst were added sequentially and stirred at high speed until homogeneous. The mixture was poured into a sealed steel mold preheated to 90°C, with a cavity filling rate of 85%. After curing at a constant temperature for 30 minutes, the mixture was demolded and allowed to mature at room temperature for 24 hours.

[0035] Table 1 Key Performance Test Data of Finished Products As can be seen from the comparison between the above embodiments and the comparative embodiments: (1) Significantly improved cell quality. The cells in Examples 1 to 3 all exhibited uniform and fine characteristics, without macropores or through-cell defects. This is attributed to the high molecular properties of the CO2-based block copolymer, which enabled it to achieve thermodynamically stable molecular-level dispersion in the silicon matrix. The terminal hydroxyl groups served as foaming active sites and were evenly distributed, allowing the hydrogen release process to occur synchronously in all regions.

[0036] (2) Significantly improved mechanical properties. The tear strengths of Examples 1-3 were 28.2, 32.7, and 39.5 kN / m, respectively, representing increases of 47.6%, 71.2%, and 106.8% compared to the 19.1 kN / m of the comparative example. This improvement stems from two synergistic effects: firstly, the rigid carbonate segments reinforce the silicone rubber crosslinking network through physical entanglement and hydrogen bonding; secondly, the uniform cell structure eliminates the stress concentration effect caused by macropores and bubble breakage. The compression set decreased from 13.8% in Comparative Example 1 to 8.2%, 6.3%, and 4.1%, respectively, reflecting the improved resilience stability resulting from the combined effects of optimized cell structure and reinforcement.

[0037] (3) Breakthrough in low-temperature toughness. No cracks or whitening were observed in the three examples during the 180° bending test at -35°C, while the comparative example showed multiple fractures. This difference stems from the fact that the polyether soft segments impart good low-temperature flexibility to the molecular chains, and their glass transition temperature is much lower than -35°C. At extreme low temperatures, the chain segments can still move freely, effectively dissipating bending stress and avoiding the brittle fracture caused by the freezing of chain segments in traditional pure silicone foam.

[0038] (4) Excellent chemical corrosion resistance. All three examples showed no swelling or cracking after immersion in 5% sulfuric acid and 5% sodium hydroxide solutions at room temperature for 168 hours, while the comparative example showed significant swelling and corner cracking. This is because the formulation of this invention contains no free small molecule alcohol and water residue, eliminating the root cause of small molecule migration and hydrolysis catalyzing silicon chain degradation; the carbonate segments themselves have a certain degree of chemical corrosion resistance; and the uniform and dense pore structure reduces the penetration channels of corrosive media.

[0039] (5) Functional graded product capability. By adjusting the hydroxyl value, dosage, and filler combination of the block copolymer, this invention achieves a product range from low-density slow-rebound open-cell foam (Example 1, density 0.20 g / cm³) to high-density open-cell foam. 3 From high-density, wear-resistant, and corrosion-resistant closed-cell foam (Example 3, density 0.48 g / cm³, rebound time 3.2 s) to high-density, wear-resistant, and corrosion-resistant closed-cell foam (Example 3, density 0.48 g / cm³). 3 Our full range of products (including high-support rigid foam) covers the entire spectrum of products to meet the differentiated needs of different application scenarios.

[0040] Comparative analysis of Examples 1-3 and Example 2: In Comparative Example 2, ethylene glycol locally agglomerates in the silicon matrix due to polarity differences, resulting in uneven gas production during the foaming stage, leading to a mixture of large and small pores and interconnected bubble breakage. In Comparative Example 3, although the ordinary polyether improves compatibility with the silicon matrix and enhances pore uniformity, it lacks rigid carbonate segments, resulting in insufficient pore wall strength and still exhibiting the problem of oversized pores. In Example 2, the CO2-based block copolymer is dispersed at the molecular level in the silicon matrix, resulting in regular and dense pores.

[0041] Regarding tear strength, Comparative Example 2 showed 19.5 kN / m, while Comparative Example 3 increased to 23.8 kN / m (an increase of approximately 22%), indicating that the polyether structure itself has a certain toughening effect on silicone rubber. However, Example 2 reached 32.7 kN / m, an increase of 67.7% compared to Comparative Example 2 and 37.4% compared to Comparative Example 3. This proves that the rigid carbonate segments introduced by CO2 copolymerization, through physical entanglement and hydrogen bonding, provide a rigid reinforcement effect on the silicone rubber network, which is the key factor for the significant increase in tear strength, and cannot be replaced by the simple polyether structure.

[0042] Regarding low-temperature toughness, Comparative Example 2 fractured and cracked in multiple places during bending at -35℃; Comparative Example 3 showed improvement but still exhibited microcracks and whitening; Example 2 showed no cracks or whitening. The polyether soft segments impart low-temperature flexibility, which is the basis for low-temperature toughness, but the uniform hybrid structure formed by the carbonate segments and silicone rubber network further eliminates stress concentration points. Regarding chemical corrosion resistance, Comparative Example 2 showed significant swelling and cracking due to hydrolysis catalysis caused by residual small-molecule alcohols; Comparative Example 3, although without small-molecule migration issues, still showed slight swelling due to insufficient chemical resistance of ordinary polyether; Example 2, due to the chemical corrosion resistance of the carbonate segments and its uniform and dense cell structure, showed no swelling or cracking.

[0043] In summary, the advantages of CO2-based block copolymers as hydrogen sources are reflected in three aspects: their high molecular properties enable molecular-level dispersion, resulting in uniform cell structure; the rigid segments of carbonate provide reinforcement, significantly improving mechanical properties; and the synergistic effect of the soft segments of polyether and the hard segments of carbonate achieves both low-temperature toughness and corrosion resistance. Ordinary polyethers can only achieve partial improvements and cannot replicate the rigid reinforcement and chemical corrosion resistance advantages brought by carbonate segments.

[0044] The CO2-based block copolymer used in this invention uses industrial waste gas CO2 as a comonomer. During the polymerization reaction, CO2 is chemically bonded and fixed into the polymer molecular chain, forming stable carbonate segments that will not be released again throughout the entire life cycle of the foam product. Taking Example 2 as an example, the block copolymer accounts for approximately 22.3% of the formulation by mass, and the CO2 structural units in the copolymer account for 35% by mass (typical value). The carbon fixation amount per kilogram of foam is approximately 22.3% × 35% × 1000 ≈ 78.1 g / kg. Taking Example 3 as an example, the block copolymer accounts for approximately 22.9% by mass, and the CO2 structural units account for 40% by mass. The carbon fixation amount per kilogram of foam is approximately 22.9% × 40% × 1000 ≈ 91.6 g / kg. The carbon fixation amount exhibits permanent stability throughout the product's life cycle because CO2 is embedded in the polymer backbone in the form of carbonate bonds. It only decomposes under the synergistic effects of strong acids, strong alkalis, and high temperatures, far exceeding the normal operating conditions of foam products.

Claims

1. A carbon dioxide-based block polyether self-hydrogen-supporting modified liquid silicone foam, wherein the raw material composition comprises vinyl polysiloxane, hydrogen-containing silicone oil, and platinum-based catalyst, characterized in that, The composition also contains a hydroxyl-terminated polycarbonate-polyether block copolymer obtained by copolymerizing carbon dioxide and epoxy alkane; The molecular chain of the block copolymer is composed of polycarbonate hard segments and polyether soft segments forming a block structure, with a hydroxyl group at each end of the molecular chain; The terminal hydroxyl groups undergo a dehydrogenation condensation reaction with the Si-H bonds in the hydrogen-containing silicone oil to release hydrogen gas, which serves as the gas source for foaming the composition. The polycarbonate hard segments form physical entanglements and hydrogen bond interactions in the silicone rubber crosslinking network, constituting a reinforcing structure; The polyether soft segments provide the ability for compliant molecular chain movement at low temperatures.

2. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, The number-average molecular weight of the copolymer is 2000–8000 g / mol.

3. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, In the block copolymer, the polycarbonate hard segments are formed by alternating copolymerization of carbon dioxide and propylene oxide, and the polyether soft segments are formed by homopolymerized segments of propylene oxide or homopolymerized segments of ethylene oxide.

4. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, In the block copolymer, carbon dioxide structural units account for more than 30% of the total mass of the copolymer, and the hydroxyl value of the copolymer is 40 mg KOH / g to 72 mg KOH / g.

5. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, The raw material composition of the composition, by weight, includes: 60-90 parts of vinyl polysiloxane; 5-35 parts of the block copolymer; 3-12 parts of hydrogen-containing silicone oil; 0.001-0.05 parts of platinum-based catalyst; and 0-25 parts of inorganic filler.

6. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, The block copolymer with a hydroxyl value of 40–48 mg KOH / g was used to prepare a product with a density of 0.15–0.25 g / cm³. 3 Slow-rebound open-cell foam; the block copolymer with a hydroxyl value of 58–63 mg KOH / g is used to prepare a density of 0.25–0.40 g / cm³. 3 A general-purpose cushioning foam; the block copolymer with a hydroxyl value of 67–72 mgKOH / g is used to prepare a density of 0.40–0.60 g / cm³. 3 High-support foam.

7. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 1, characterized in that, The vinyl polysiloxane is α,ω-divinyl polydimethylsiloxane, with a vinyl content of 0.1 mol% to 1.5 mol%; the hydrogen-containing silicone oil is a side-hydrogen type polyorganosiloxane, with an active hydrogen content of 0.5 wt% to 1.6 wt%; the platinum-based catalyst is a chloroplatinic acid-vinylsiloxane complex.

8. The carbon dioxide-based block polyether self-hydrogen-supplying modified liquid silicone foam according to claim 5, characterized in that, The inorganic filler is selected from one or more of fumed silica, light calcium carbonate, and aluminum hydroxide; the specific surface area of ​​the fumed silica is 150 m². 2 / g~300m 2 / g, wherein the median particle size of the aluminum hydroxide is 1μm to 5μm.

9. The method for preparing carbon dioxide-based block polyether self-hydrogen-donating foamed modified liquid silicone foam according to any one of claims 1 to 8, characterized in that, Includes the following steps: The vinyl polysiloxane is mixed with the block copolymer to form a homogeneous mixture, thereby dispersing the block copolymer at the molecular level in the matrix; Hydrogen-containing silicone oil and platinum-based catalyst are added to the mixture and mixed thoroughly. The obtained composition is injected into a mold and kept at 60℃~130℃ for 10min~60min to allow the hydrosilylation crosslinking reaction and the terminal hydroxyl dehydrogenation gas generation reaction to proceed simultaneously. Hydrogen gas is uniformly nucleated and foamed in the crosslinking network and then solidified.

10. The method for preparing carbon dioxide-based block polyether self-hydrogen-donating modified liquid silicone foam according to claim 9, characterized in that, The material temperature is controlled below 35℃ during the mixing process; the mold cavity filling rate is 60% to 95%; the curing temperature is positively correlated with the hydroxyl value of the block polyether.

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