A melt-blown nonwoven material and its method of manufacture and use

Abstract

The application provides a melt-blown non-woven material and a preparation method and application thereof, raw materials of the melt-blown non-woven material include a phenolic resin; the weight average molecular weight of the phenolic resin is greater than or equal to 1800, the number average molecular weight is greater than or equal to 1270; under the condition of 150 DEG C and a shear rate of 2500 s ‑1 -1, the viscosity of the phenolic resin is 1-3 mPa.s, and the melt index is greater than 1000 g / 10min. In the application, the phenolic resin with specific molecular weight, viscosity and melt index is used for preparing the melt-blown non-woven material, the melt-blown non-woven material has good spinnability, excellent toughness and thermal stability, excellent flame-retardant performance and thermal insulation performance, high residual carbon rate and low thermal shrinkage rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thermal protection materials, and particularly relates to a melt-blown non-woven material and a preparation method and application thereof. BACKGROUND

[0002] With the continuous progress of society, people's living standards are constantly improving, but the fire personnel casualties caused by many fire accidents in recent years are heart-wrenching, and the injuries of employees caused by fires, explosions and other accidents in various production enterprises also ring the alarm bell for us to focus on personal protection of production personnel; Therefore, we need to focus on personal thermal protection textiles for flame retardation, high temperature resistance and thermal insulation.

[0003] Over the past few decades, researchers have developed a variety of thermal insulation materials for personal thermal protection products, such as aerogels, polymer foams, glass fibers, and electrospun fiber mats, but these materials have not been accepted by the market due to complex production processes, poor softness and comfort, and the risk of physical injury to users. The main commercial personal thermal protection products currently use aramid spunlace fiber mats, which are mixed with meta-aramid and para-aramid in proportion, carded into a web, and then solidified by water jet method. Although this product has the flame retardant characteristics of aramid fiber and the web structure of spunlace non-woven fabric, it still has the following obvious problems: ① aramid spunlace products will shrink significantly in size after long-term heating, affecting their protective performance, ② the porosity of spunlace non-woven fabric is not high, and the performance of the thermal insulation product prepared by this method is slightly insufficient, ③ aramid spunlace products will become hard when exposed to open flames, which will affect the user's activities while losing thermal insulation performance, ④ aramid fiber thermal cracking will release a large amount of volatile organic compounds, causing secondary injury to the user, ⑤ aramid fiber itself has a high cost, resulting in high prices of personal thermal protection products, and high-quality products are difficult to be widely adopted. In summary, it is an urgent need to develop a personal thermal protection material with excellent web structure, intrinsic flame retardant properties, mature production process, and broad application prospects to promote social stability, continuous and rapid development.

[0004] Melt blowing is a special melt spinning method, which has simple principle, fast production speed and low operation complexity. The thermoplastic polymer resin can be directly prepared into melt-blown non-woven material with nano-micro structure by using the method, and the material has the characteristics of high porosity, small pore size and soft texture, which is very suitable for personal thermal protection field. The melt-blown non-woven fabric has a wide range of raw material selection, and the commonly used raw materials at present are polypropylene, polyester, polylactic acid and the like, but these materials are thermoplastic materials, which are difficult to bring the required protection performance to the user in a high temperature environment, and the melt drops generated after melting will adhere to the skin of the user, thereby causing serious secondary injury. In addition, flame-retardant finishing of melt-blown non-woven fabric is also a commonly used method, but these finishing agents are mostly in the form of adhesion on the surface of the fiber, which is difficult to withstand long-term use, and the mechanism does not change the thermoplasticity of the original fiber, so the effect is not obvious, and it is not widely recognized in the market.

[0005] Therefore, it is an urgent problem in the art to develop a melt-blown non-woven material with good heat resistance, low thermal shrinkage, excellent flame-retardant performance and thermal insulation performance, and good flexibility. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a melt-blown non-woven material and a preparation method and application thereof. The melt-blown non-woven material has excellent flame-retardant performance, thermal insulation performance and flexibility, and high carbon residue rate and low thermal shrinkage.

[0007] To achieve this purpose, the technical scheme adopted by the present application is as follows:

[0008] In a first aspect, the present application provides a melt-blown non-woven material, wherein the raw material of the melt-blown non-woven material comprises a phenolic resin; the weight average molecular weight (Mw) of the phenolic resin is greater than or equal to 1800, and the number average molecular weight (Mn) is greater than or equal to 1270; under the condition of 150 DEG C and shear rate of 2500 s -1 , the viscosity of the phenolic resin is 1-3 mPa.s, and the melt index is greater than 1000 g / 10 min.

[0009] In the present application, the phenolic resin with specific weight average molecular weight and number average molecular weight, and specific melt index and viscosity has good spinnability, and is used for preparing melt-blown non-woven material, which is beneficial to improve the carbon residue rate of the material, reduce the thermal shrinkage, and make the melt-blown non-woven material have excellent flame-retardant performance, thermal insulation performance and flexibility, and good thermal protection performance.

[0010] In the present application, the weight average molecular weight of the phenolic resin is ≥1800, for example, it can be 1800, 1850, 1900, 1950, 2000, 2050, 2100, 2150, 2200, 2250, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3200, 3400, 3600, 3800, 4000, etc.; the number average molecular weight is ≥1270, for example, it can be 1270, 1280, 1300, 1320, 1340, 1360, 1380, 1400, 1420, 1450, 1460, 1480, 1500, 1520, 1550, 1580, 1600, 1620, 1650, 1680, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, etc.

[0011] In the present application, the viscosity of the phenolic resin is 1-3 mPa.s, for example, it can be 1 mPa.s, 1.2 mPa.s, 1.4 mPa.s, 1.6 mPa.s, 1.8 mPa.s, 2 mPa.s, 2.1 mPa.s, 2.2 mPa.s, 2.3 mPa.s, 2.4 mPa.s, 2.5 mPa.s, 2.6 mPa.s, 2.7 mPa.s, 2.8 mPa.s, 2.9 mPa.s, 3 mPa.s, etc.; the melt index is >1000 g / 10 min, for example, it can be 1020 g / 10 min, 1040 g / 10 min, 1060 g / 10 min, 1080 g / 10 min, 1100 g / 10 min, 1150 g / 10 min, 1200 g / 10 min, 1250 g / 10 min, 1300 g / 10 min, 1350 g / 10 min, 1400 g / 10 min, 1450 g / 10 min, 1500 g / 10 min, 1520 g / 10 min, 1540 g / 10 min, 1560 g / 10 min, 1580 g / 10 min, 1600 g / 10 min, 1620 g / 10 min, 1640 g / 10 min, 1660 g / 10 min, 1680 g / 10 min, 1700 g / 10 min, 1720 g / 10 min, 1750 g / 10 min, 1780 g / 10 min, 1800 g / 10 min, 1820 g / 10 min, 1850 g / 10 min, 1880 g / 10 min, 1900 g / 10 min, 1920 g / 10 min, 1950 g / 10 min, 1980 g / 10 min, 2000 g / 10 min, etc.

[0012] In the present application, the viscosity and melt index of the phenolic resin within the above defined range is advantageous to improve the spinnability of the phenolic resin.

[0013] Preferably, the weight average molecular weight of the phenolic resin is 1810-3000.

[0014] Preferably, the number average molecular weight of the phenolic resin is 1270-2000.

[0015] Preferably, the viscosity of the phenolic resin is 2-3 mPa.s and the melt index is >1500 g / 10 min at 150℃ and shear rate of 2500 s -1

[0016] Preferably, the molecular weight distribution index of the phenolic resin is 1.32-1.5, for example, it can be 1.32, 1.34, 1.36, 1.38, 1.4, 1.42, 1.44, 1.46, 1.48, 1.5, etc.

[0017] In the present application, too small molecular weight or too wide molecular weight distribution of the phenolic resin will result in difficulty in forming during processing, and the fiber will be easily broken after melt processing and cooling, resulting in discontinuous production or even failure to form.

[0018] Preferably, the phenolic resin comprises a high ortho-phenolic resin.

[0019] Preferably, the ortho-para ratio of the phenolic resin is 1.1-4, for example, it can be 1.1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.73, 3.8, 3.85, 3.87, 3.89, 3.9, 3.92, 3.94, 3.96, 3.98, 4, etc.

[0020] In the present application, the high ortho-phenolic resin refers to a phenolic resin with ortho-para ratio greater than 1; the use of high ortho-phenolic resin has better spinnability and faster crosslinking reaction speed.

[0021] Preferably, the glass transition temperature (Tg) of the phenolic resin is 80-100℃, for example, it can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, etc.

[0022] Preferably, the raw materials for preparing the phenolic resin comprise phenolic compounds and aldehyde compounds.

[0023] ​Preferably, the molar ratio of the phenolic compound and the aldehyde compound is 1:(0.7-0.85), which can be 1:0.7, 1:0.72, 1:0.75, 1:0.78, 1:0.8, 1:0.82, 1:0.85, etc.

[0024] In the present application, the phenolic compound includes but is not limited to phenol; and the aldehyde compound includes but is not limited to formaldehyde.

[0025] Preferably, the raw material for preparing the phenolic resin further includes a modifier.

[0026] Preferably, the modifier includes siloxane and / or boric acid.

[0027] In the present application, the phenolic resin is modified by siloxane, a flexible chain containing silicon element is introduced into the molecular chain of the phenolic resin, so as to achieve the chain extension and toughening effect of the original methylene rigid chain of the phenolic resin, and the obtained siloxane modified phenolic resin has better flexibility and good spinnability; the phenolic resin is doubly modified by siloxane and boric acid, on the basis of improving the toughness, the boric acid can further react with the hydroxyl group on the phenolic resin, which is conducive to improving the thermal degradation performance of the resin, and the boric acid can also participate in the crosslinking reaction to form a more firm three-dimensional network structure, greatly improving the thermal stability performance of the resin, and the resin has good spinnability; all of which can meet the requirements of melt spinning by melt-blowing method.

[0028] Preferably, the mass of the siloxane is 3-12% based on 100% of the mass of the phenolic compound, which can be 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, 10.2%, 10.5%, 10.8%, 11%, 11.2%, 11.5%, 11.8%, 12%, etc.

[0029] Preferably, the siloxane includes small molecule siloxane and / or polysiloxane.

[0030] Preferably, the siloxane includes small molecule siloxane and polysiloxane, and the mass ratio of the small molecule siloxane and the polysiloxane is 1:(0.3-0.75), which can be 1:0.3, 1:0.32, 1:0.35, 1:0.38, 1:0.4, 1:0.42, 1:0.45, 1:0.48, 1:0.5, 1:0.52, 1:0.55, 1:0.58, 1:0.6, 1:0.62, 1:0.65, 1:0.68, 1:0.7, 1:0.72, 1:0.75, etc.

[0031] Preferably, the small molecule siloxane comprises any one or a combination of at least two of dimethyldimethoxysilane, gamma-aminopropyltriethoxysilane or gamma-glycidoxypropyltrimethoxysilane.

[0032] Preferably, the polysiloxane comprises polydimethylsiloxane.

[0033] Preferably, the mass of the boric acid is 3-9% based on 100% of the mass of the phenolic compound, for example, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.4%, 8.6%, 8.8%, 9%, etc.

[0034] Preferably, the phenolic resin is prepared by a method comprising:

[0035] The phenolic resin is obtained by condensation polymerization of the phenolic compound and the aldehyde compound in the presence of a divalent metal salt.

[0036] In the present application, the divalent metal salt is a catalyst, comprising any one or a combination of at least two of zinc acetate, zinc chloride, magnesium chloride or magnesium sulfate; the mass of the divalent metal salt is 6-10% based on 100% of the mass of the phenolic compound, for example, 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.4%, 8.6%, 8.8%, 9%, 9.2%, 9.4%, 9.6%, 9.8%, 10%, etc.

[0037] In the present application, the pH value of the condensation polymerization is 4-7, for example, 4, 5, 6, 7, etc.; the temperature is 70-120°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.; and the time is 0.5-1.5h, for example, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, etc.

[0038] In the present application, under the catalysis of the divalent metal salt, high ortho-phenolic resin can be induced to generate, thereby effectively improving the spinnability and shortening the time required for crosslinking reaction.

[0039] In some embodiments, after the polycondensation reaction, the product of the polycondensation reaction is further reacted with a modifying agent; the modifying agent can be siloxane, can be boric acid, can be both siloxane and boric acid, and the order of adding the siloxane and the boric acid can be that the siloxane is added first for modification, or the boric acid is added first for modification.

[0040] In some embodiments, the step of reacting the product of the polycondensation reaction with a modifying agent comprises: reacting the product of the polycondensation with siloxane to obtain a siloxane-modified phenolic resin; and then reacting the siloxane-modified phenolic resin with boric acid to obtain the phenolic resin.

[0041] In the present application, the temperature for reacting the product of the polycondensation with siloxane is 70-120℃, for example, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.; and the time is 2-8h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0042] Preferably, the pH value for reacting the siloxane-modified phenolic resin with boric acid is 1-3, for example, 1, 2, 3, etc.; the temperature is 70-120℃, for example, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc.; and the time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0043] Preferably, after the polycondensation reaction or after the addition of the modifying agent, the product is further subjected to a step of vacuum distillation and / or drying.

[0044] In the present application, the purpose of the vacuum distillation is to purify and remove impurities, and to distill off the solvent; the temperature for the vacuum distillation is 150-170℃, and the time is 1-3h.

[0045] In the present application, the drying comprises drying and further removing the residual solvent in a vacuum environment or a protective gas environment, and the drying temperature is 110-130℃, and the time is 3-8h.

[0046] In the present application, the synthesis reaction environment of phenolic resin is mostly water environment. In order to remove small molecular components after the synthesis reaction is completed, further treatment is required. Specifically, the synthesized phenolic resin is washed with distilled water for multiple times, and then the washed resin is dissolved with anhydrous ethanol. Subsequently, the ethanol is evaporated by using a reduced pressure distillation method, and volatile small molecules are carried out. The resin after the reduced pressure distillation has high purity in theory. However, in order to adapt to the process requirements of large-scale melt-blown melt spinning, the resin still needs to be further evaporated and dried. In this step, in order to prevent the resin from being oxidized for a long time, the resin needs to be dried in a vacuum environment or a protective gas environment. The resin prepared through the above steps meets the performance requirements of the subsequent melt-blown process and use scenarios.

[0047] In the present application, the fiber diameter of the melt-blown non-woven material is 0.8-8 μm, for example, it can be 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.2 μm, 5.5 μm, 5.8 μm, 6 μm, 6.2 μm, 6.5 μm, 6.8 μm, 7 μm, 7.2 μm, 7.5 μm, 7.8 μm, 8 μm, etc.

[0048] Preferably, the porosity of the melt-blown non-woven material is >70%, for example, it can be 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, etc.

[0049] In the present application, the reason why the melt-blown non-woven material has a low thermal conductivity is mainly due to its ultra-fine fiber structure. This feature can effectively reduce the transmission path of solid heat conduction. At the same time, the structure characteristics of high porosity and small pore size effectively control heat convection and heat radiation. The synergistic effect of the two effectively reduces the heat conduction inside the non-woven material, so that it obtains excellent thermal insulation performance.

[0050] In a second aspect, the present application provides a preparation method of the melt-blown non-woven material according to the first aspect, and the preparation method comprises:

[0051] The phenolic resin is melt-blown and cross-linked to obtain the melt-blown non-woven material.

[0052] In the present application, before melt-blown, the phenolic resin further comprises a step of drying at 60-120 ℃ for 2-8 h.

[0053] Preferably, the melt-blown device comprises a melt-blown machine.

[0054] Preferably, the melt temperature of the melt-blown is 100-165℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 155℃, 156℃, 157℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, etc.

[0055] Preferably, the hot air drawing temperature of the melt-blown is 100-170℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 162℃, 164℃, 166℃, 168℃, 170℃, etc.

[0056] Preferably, the receiving distance during drawing is 25-50cm, for example, it can be 25cm, 30cm, 35cm, 40cm, 45cm, 50cm, etc.

[0057] The melt-blown method is a method that can directly convert resin raw materials into ultra-fine fiber non-woven materials, and has the characteristics of simple process, fast production speed and wide product application. Due to its unique web forming method, ultra-fine fiber diameter, high porosity and small pore size, melt-blown non-woven fabrics are often used in the field of warmth preservation. However, since the resin raw materials used in this method are all thermoplastic resins, and the glass transition temperature is usually not high, melt-blown non-woven fabrics are rarely used in the field of thermal insulation. In the present application, a phenolic resin with a specific molecular weight and molecular weight distribution, as well as a specific viscosity and melt index, is used to realize the transformation from thermoplastic to thermoset through subsequent reactions, and is used to prepare melt-blown non-woven materials, perfectly combining the high thermal insulation performance of melt-blown materials and the flame retardant properties of phenolic resins.

[0058] Preferably, the cross-linking bath for cross-linking is a mixture of compound A and compound B; the compound A includes any one or a combination of at least two of hydrochloric acid, phosphoric acid, oxalic acid or dilute sulfuric acid; the compound B includes any one or a combination of at least two of formaldehyde, trioxane or hexamethylenetetramine.

[0059] In the present application, the solid-liquid ratio during cross-linking is 1:(1-100), and the specific value in (1-100) can be, for example, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 65, 70, 75, 80, 85, 90, 100, etc.; the solid-liquid ratio refers to the mass ratio of the fibrillar material obtained by drawing to the cross-linking bath.

[0060] Preferably, the mass fraction of compound A in the crosslinking bath is 10-25%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%, etc.; the mass fraction of compound B is 10-25%, for example, it can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%, etc., and the balance is water.

[0061] Preferably, the crosslinking includes the steps of pre-soaking and temperature rising curing of the drawn fiber material in the crosslinking bath.

[0062] Preferably, the pre-soaking temperature is room temperature, and the time is 0.5-2h, for example, it can be 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc., preferably 1.5-2h.

[0063] Preferably, the heating rate of the temperature rising is 1-35℃ / h, for example, it can be 1℃ / h, 2℃ / h, 4℃ / h, 5℃ / h, 6℃ / h, 8℃ / h, 10℃ / h, 12℃ / h, 14℃ / h, 16℃ / h, 18℃ / h, 20℃ / h, 22℃ / h, 24℃ / h, 26℃ / h, 28℃ / h, 30℃ / h, 32℃ / h, 34℃ / h, 35℃ / h, etc.; preferably 13-20℃ / h; the temperature is raised to 100-120℃, for example, it can be 100℃, 105℃, 110℃, 115℃, 120℃, etc.; and after the temperature rising, the temperature is kept for 0.5-3h, for example, it can be 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, etc.

[0064] In the present application, the crosslinking bath is used for curing, which is different from the traditional flame-retardant finishing method of attaching flame retardants to the surface of the material. In this reaction, the crosslinking bath will completely react with each fiber of the phenolic resin melt-blown material from the outside to the inside, and all of them will become flame-retardant fibers without adding flame retardants, which is called intrinsic flame retardance. As for the components of the crosslinking bath, it mainly consists of hydrogen ion donor and methylene donor, among which the hydrogen ion donor is mostly acid, and the methylene donor is mostly aldehyde or a substance that can react with acid to generate aldehyde. In the crosslinking bath, the two first generate CH2OH ion, which will diffuse from the fiber skin layer to the core layer. At the same time, because the fiber skin layer is heated more, a dense sheath layer will be gradually formed, which can prevent the fiber from swelling and breaking under the action of the solution, but at the same time, if the sheath layer is too dense, it will also prevent the CH2OH ion from diffusing to the core layer. + CH2OH ion, which will diffuse from the fiber skin layer to the core layer. At the same time, because the fiber skin layer is heated more, a dense sheath layer will be gradually formed, which can prevent the fiber from swelling and breaking under the action of the solution, but at the same time, if the sheath layer is too dense, it will also prevent the CH2OH ion from diffusing to the core layer. +The inward penetration of CH2OH ions, thus the characteristics of the fiber diameter in the melt-blown non-woven material in the present application, is ingeniously regulated by controlling the concentration of the substance in the cross-linking bath and the heating rate to regulate the formation of the sheath, and the best balance between the cross-linking effect and the reaction time is achieved.

[0065] In the present application, if the pre-soaking step is not performed, the concentration of CH2OH ions in the cross-linking bath will be too high + When the cross-linking reaction starts to occur on the surface of the fiber before the CH2OH ions have fully penetrated the fiber, the fiber forms a clear skin-core structure, and the three-dimensional structure of the melt-blown fiber collapses, which greatly affects the basic physical properties and subsequent use performance; in addition, when the temperature is raised for solidification, the heating rate is too fast, causing the concentration of CH2OH ions inside and outside the fiber to be too different during the reaction + When the concentration of CH2OH ions is too different, and the skin layer is too thin, the fiber swells and fails to achieve the expected product.

[0066] Preferably, the cross-linking further comprises a washing and drying step.

[0067] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0068] The phenolic resin is dried at 60-120℃ for 2-8h, and then melt-blown under the conditions of a temperature of 100-165℃, a hot air drawing temperature of 100-170℃, and a receiving distance during drawing of 25-50cm to obtain a fiber material; then the obtained fiber material is soaked in a cross-linking bath at room temperature for 0.5-2h, heated from room temperature to 100-120℃ at a heating rate of 1-35℃ / h and kept at 100-120℃ for 0.5-3h, washed and dried to obtain the melt-blown non-woven material.

[0069] In the present application, the washing and drying comprises washing the solidified fiber with deionized water for two to three times, and then heat treating at 120-250℃ for 1-3h to obtain the phenolic melt-blown non-woven material.

[0070] In a third aspect, the present application provides a thermal protection product, wherein the material of the thermal protection product comprises the melt-blown non-woven material according to the first aspect.

[0071] The numerical range in the present application not only includes the point values listed above, but also includes any point values between the above numerical ranges that are not listed, and for the sake of brevity and simplicity, the present application does not exhaustively list the specific point values included in the range.

[0072] Compared with the prior art, the present application has the following beneficial effects:

[0073] The melt-blown non-woven material prepared by using the phenolic resin with specific molecular weight and molecular weight distribution has the advantages of high carbon residue rate, low thermal shrinkage rate, excellent flame retardant performance, thermal insulation performance and flexibility, and good thermal protection performance. The carbon residue rate of the melt-blown non-woven material is greater than 60%, the thermal shrinkage rate is less than or equal to 2.3%, the TPP value is greater than 34 cal / cm 2 , the thermal conductivity is less than 0.037 W·m -1 ·K -1 , and the limiting oxygen index is greater than or equal to 31. DETAILED DESCRIPTION

[0074] The technical solutions of the present application are further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0075] Preparation Example 1

[0076] The present preparation example provides a phenolic resin (PR-1), and the preparation method of the phenolic resin comprises the following steps:

[0077] Phenol and formaldehyde solution are weighed in a reaction container according to a molar ratio of 1:0.8, 4% zinc acetate (based on 100% phenol mass content) is added thereto, and after stirring at 70°C for 1h to mix the three, concentrated hydrochloric acid is added to the reaction system to a pH value of 4, and 7% (based on 100% phenol mass content) of a mixture of dimethyldimethoxysilane and polydimethylsiloxane (mass ratio of 1:0.4) is added, and after mixing, the temperature is raised to 100°C and reacted for 4h; then concentrated hydrochloric acid is added to the reaction system to a pH value of 3, and 6% boric acid (based on 100% phenol mass content) is added to continue the reaction for 2h; sodium hydroxide solution is added to the reaction system to adjust the pH value of the system to 5, the resin is washed with deionized water and treated by reduced pressure distillation at 170°C for 2h, and finally the resin is dried in a vacuum oven at 120°C under vacuum conditions for 6h to obtain the phenolic resin.

[0078] Preparation Example 2

[0079] The present preparation example provides a phenolic resin (PR-2), which is different from the preparation example 1 only in that the content of the siloxane modifier in the preparation method of the phenolic resin is 10%, which is a mixture of γ-aminopropyl triethoxysilane and polydimethylsiloxane (mass ratio of 1:0.6), and the other raw materials, amounts, steps and parameters are the same as those of the preparation example 1.

[0080] Preparation Example 3

[0081] The present preparation example provides a phenolic resin (PR-3), which is only different from the preparation example 1 in that the mass ratio of dimethyldimethoxysilane and polydimethylsiloxane is 1:0.1 in the preparation method of the phenolic resin, and the other raw materials, amounts, steps and parameters are the same as those in the preparation example 1.

[0082] Preparation example 4

[0083] The present preparation example provides a phenolic resin (PR-4), which is only different from the preparation example 1 in that the mass ratio of dimethyldimethoxysilane and polydimethylsiloxane is 1:1.2 in the preparation method of the phenolic resin, and the other raw materials, amounts, steps and parameters are the same as those in the preparation example 1.

[0084] Preparation example 5

[0085] The present preparation example provides a phenolic resin (PR-5), which is only different from the preparation example 1 in that no boric acid modifier is added in the preparation method of the phenolic resin, but the resin is washed with deionized water after reacting for 6 h at 100 ℃ and the subsequent steps are continued, and the other raw materials, amounts, steps and parameters are the same as those in the preparation example 1.

[0086] Preparation example 6

[0087] The present preparation example provides a phenolic resin (PR-6), which is only different from the preparation example 1 in that only dimethyldimethoxysilane is used as the siloxane modifier in the preparation method of the phenolic resin, and the other raw materials, amounts, steps and parameters are the same as those in the preparation example 1.

[0088] Preparation example 7

[0089] The present preparation example provides a phenolic resin (PR-7), which is only different from the preparation example 1 in that only polydimethylsiloxane is used as the siloxane modifier in the preparation method of the phenolic resin, and the other raw materials, amounts, steps and parameters are the same as those in the preparation example 1.

[0090] Comparative preparation example 1

[0091] The present comparative preparation example provides a phenolic resin (PR-d1), which is only different from the preparation example 1 in that the phenolic resin is not modified by boric acid; in the preparation method, no boric acid is added for reaction, and the subsequent treatment steps are directly performed, and the other raw materials, amounts and step parameters are the same as those in the preparation example 1.

[0092] Comparative preparation example 2

[0093] The present comparative preparation example provides a phenolic resin (PR-d2), which is only different from that of Preparation Example 1 in that the phenolic resin is not modified with siloxane; in the preparation method, a mixture of dimethyl dimethoxysilane and polydimethylsiloxane is not added for reaction, i.e. after refluxing and stirring at 70℃ for 1h to mix the three, concentrated hydrochloric acid is added to the reaction system to have a pH value of 4, after mixing, the temperature is increased to 100℃ and reacted for 4h, then concentrated hydrochloric acid is added to have a pH value of 3 in the reaction system, 6% boric acid is added thereto and the reaction is continued for 2h; the other raw materials, amount and step parameters are the same as those of Preparation Example 1.

[0094] The molecular weight, glass transition temperature, ortho / para ratio and spinnability of the phenolic resins provided by Preparation Examples 1-7 and Comparative Preparation Examples 1 and 2 are characterized, and the results are shown in Table 1.

[0095] Among them, the molecular weight is determined by gel permeation chromatography, the solvent used is N,N-dimethylformamide (DMF), and the weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution index (molecular weight distribution index D = Mw / Mn) are used as the main characterization data.

[0096] Glass transition temperature (Tg): determined by differential scanning calorimetry; the specific method comprises: using a DSC200F3 differential scanning calorimeter to determine the glass transition temperature, selecting 10mg modified phenolic resin, and heating from 20℃ to 100℃ at a rate of 10℃ / min, after cooling to room temperature, heating to 200℃ at a rate of 10℃ / min, the whole process is carried out in a nitrogen environment, and the data of the second heating process is taken.

[0097] Ortho / para ratio: characterized by liquid nuclear magnetic resonance method, the actual ortho / para ratio is obtained by integrating and calculating the characteristic peaks of the liquid nuclear magnetic resonance spectrum according to the formula, when the value is greater than 1, the resin is usually called high ortho phenolic resin, and the formula is as follows:

[0098]

[0099] In the formula, Ao-o', Ao-p' and Ap-p' are the integral values of the characteristic peak intensities corresponding to o-o' (ortho-ortho), o-p' (ortho-para) and p-p' (para-para) in NMR test, respectively.

[0100] Spinnability: two dimensions of rheological properties and melt index are used for evaluation; rheology plays an important role in the study of the flow and deformation ability of polymers in the process, and the melt spinning equipment of melt blowing method in industrial production is mostly screw type, and rheological test can simulate the shearing action of high polymer in screw very close, which can be more close to the actual production condition, all the phenolic resins prepared in the application are typical non-Newtonian fluid, the viscosity decreases with the increase of shear rate, the reason is that with the increase of shear rate, the increase of the disentanglement rate of macromolecules is greater than the increase of the entanglement rate, at the same time, the free volume and degree of freedom of chain segment increases with the increase of temperature, which leads to the decrease of the viscosity of polymer with the increase of temperature, that is, the "shear thinning" phenomenon. Therefore, in the evaluation of the spinnability of the resin, the parameters of the actual production equipment are often combined, and both too thin and too thick viscosity will be not conducive to the melt spinning. In the application, the rheological properties of the modified phenolic resin at different temperatures are tested by using MCR302 modular intelligent advanced rheometer; PP25 rotor is used, and the viscosity change is detected by setting the rotation module to shear rate-viscosity mode.

[0101] Melt flow index (melt index MFI) is a common spinnability evaluation method for direct web method nonwoven fabric of polymer, the value refers to the weight of the molten polymer melt flowing out from the standard capillary under standard load within 10 minutes at a certain temperature, and the unit is g / 10min. The high or low of the melt index not only reflects the flowability of the polymer itself, but also is closely related to the physical and mechanical properties of the fiber and web made of it, the strength and elongation at break of melt blown fabric often decrease with the increase of the melt index of the raw material, but in order to make the melt flow get better drawing in the process of hot air blowing, the MFI of the raw material is required to be as high as possible on the basis of ensuring the mechanical properties.

[0102] In the application, when the resin has a viscosity greater than or equal to 2 mPa.s and a melt index greater than 1500 g / 10min at 150 DEG C and a shear rate of 2500 s -1 -1, it is marked as very good spinnability; when the resin has a viscosity of 1-2 mPa.s and a melt index greater than 1000 g / 10min at 150 DEG C and a shear rate of 2500 s -1 -1, it is marked as good spinnability; when the resin has a viscosity of 1-2 mPa.s or a melt index greater than 1000 g / 10min at 150 DEG C and a shear rate of 2500 s -1 -1, it is marked as general spinnability; when the resin has a viscosity less than 1 mPa.s and a melt index less than 1000 g / 10min at 150 DEG C and a shear rate of 2500 s -1 -1, it is marked as poor spinnability.

[0103] The specific test results are shown in Table 1.

[0104] Table 1

[0105]

[0106] Example 1

[0107] The present embodiment provides a melt-blown non-woven material, and a preparation method thereof comprises:

[0108] (1) The phenolic resin (PR-1) is placed in a drying hopper and dried at 70°C for 2h; the end-stage heating temperature of the double-screw melt-blowing machine is set to 157°C, the hot air drawing temperature is set to 162°C, and the receiving distance is set to 30cm, to obtain an uncrosslinked modified phenolic resin melt-blown material.

[0109] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) is placed in a crosslinking device, and a crosslinking bath with a phosphoric acid mass fraction of 10wt% and a trioxane mass fraction of 20wt% is prepared at a solid-liquid ratio of 1:20; the melt-blown material is soaked in the crosslinking bath at room temperature for 2h, then heated to 100°C at a rate of 15°C / h and kept for 2h; after the melt-blown material is taken out, it is washed and dried, to obtain the melt-blown non-woven material.

[0110] Example 2

[0111] The present embodiment provides a melt-blown non-woven material, and a preparation method thereof comprises:

[0112] (1) The phenolic resin (PR-1) is placed in a drying hopper and dried at 70°C for 2h; the end-stage heating temperature of the double-screw melt-blowing machine is set to 155°C, the hot air drawing temperature is set to 160°C, and the receiving distance is set to 30cm, to obtain an uncrosslinked modified phenolic resin melt-blown material.

[0113] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) is placed in a crosslinking device, and a crosslinking bath with a phosphoric acid mass fraction of 10wt% and a trioxane mass fraction of 20wt% is prepared at a solid-liquid ratio of 1:20; the melt-blown material is soaked in the crosslinking bath at room temperature for 2h, then heated to 100°C at a rate of 15°C / h and kept for 2h; after the melt-blown material is taken out, it is washed and dried, to obtain the melt-blown non-woven material.

[0114] Example 3

[0115] The present embodiment provides a melt-blown non-woven material, and a preparation method thereof comprises:

[0116] (1) The phenolic resin (PR-1) was placed in a drying hopper and dried at 70°C for 2 h; the end zone heating temperature of the twin-screw melt-blowing machine was set to 155°C, the hot air attenuation temperature was set to 158°C, and the receiving distance was set to 25 cm to obtain the uncrosslinked modified phenolic resin melt-blown material.

[0117] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) was placed in a crosslinking device, and a crosslinking bath with a solid-liquid ratio of 1:20 was prepared by mixing oxalic acid with a mass fraction of 15 wt% and formaldehyde with a mass fraction of 15 wt%; the melt-blown material was soaked in the crosslinking bath at room temperature for 1.5 h, then heated to 100°C at a rate of 17°C / h and kept at 100°C for 2 h; after the melt-blown material was taken out, it was washed and dried to obtain the melt-blown nonwoven material.

[0118] Example 4

[0119] The present embodiment provides a melt-blown nonwoven material, and a preparation method thereof comprises:

[0120] (1) The phenolic resin (PR-1) was placed in a drying hopper and dried at 70°C for 2 h; the end zone heating temperature of the twin-screw melt-blowing machine was set to 165°C, the hot air attenuation temperature was set to 170°C, and the receiving distance was set to 35 cm to obtain the uncrosslinked modified phenolic resin melt-blown material.

[0121] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) was placed in a crosslinking device, and a crosslinking bath with a solid-liquid ratio of 1:25 was prepared by mixing oxalic acid with a mass fraction of 10 wt%, boric acid with a mass fraction of 10 wt%, and formaldehyde with a mass fraction of 20 wt%; the melt-blown material was soaked in the crosslinking bath at room temperature for 1 h, then heated to 120°C at a rate of 20°C / h and kept at 120°C for 1.5 h; after the melt-blown material was taken out, it was washed and dried to obtain the melt-blown nonwoven material.

[0122] Example 5

[0123] The present embodiment provides a melt-blown nonwoven material, and a preparation method thereof comprises:

[0124] (1) The phenolic resin (PR-1) was placed in a drying hopper and dried at 70°C for 2 h; the end zone heating temperature of the twin-screw melt-blowing machine was set to 163°C, the hot air attenuation temperature was set to 168°C, and the receiving distance was set to 30 cm to obtain the uncrosslinked modified phenolic resin melt-blown material.

[0125] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) is placed in a crosslinking device, and a crosslinking bath with a solid-liquid ratio of 1:20, a hydrochloric acid mass fraction of 15 wt%, and a hexamethylenetetramine mass fraction of 10 wt% is prepared; the melt-blown material is soaked in the crosslinking bath at room temperature for 2 h, then heated to 100°C at a rate of 15°C / h and kept at 100°C for 2 h; the melt-blown material is taken out, washed, and dried to obtain the melt-blown nonwoven material.

[0126] Example 6

[0127] The present example provides a melt-blown nonwoven material, and a preparation method thereof comprises:

[0128] (1) The phenolic resin (PR-1) is placed in a drying cylinder and dried at 70°C for 2 h; the final-stage heating temperature of a double-screw melt-blown machine is set to 163°C, the hot air drawing temperature is set to 168°C, and the receiving distance is set to 30 cm to obtain an uncrosslinked modified phenolic resin melt-blown material.

[0129] (2) The uncrosslinked modified phenolic resin melt-blown material obtained in step (1) is placed in a crosslinking device, and a crosslinking bath with a solid-liquid ratio of 1:25, a sulfuric acid mass fraction of 10 wt%, and a formaldehyde mass fraction of 15 wt% is prepared; the melt-blown material is soaked in the crosslinking bath at room temperature for 1 h, then heated to 120°C at a rate of 15°C / h and kept at 120°C for 2 h; the melt-blown material is taken out, washed, and dried to obtain the melt-blown nonwoven material.

[0130] Example 7

[0131] The present example provides a melt-blown nonwoven material, which is different from Example 1 only in that the phenolic resin is obtained by condensation polymerization of phenol and formaldehyde, no modifier is added, the Mw is 2413, the Mn is 1637, and the molecular weight distribution is 1.47, and the other preparation methods are the same as those in Example 1.

[0132] Examples 8-13

[0133] Examples 8-13 respectively provide a melt-blown nonwoven material, which is different from Example 1 only in that the phenolic resin in the preparation method is the phenolic resin provided in Preparation Examples 2-7, and the other steps and parameters are the same as those in Application Example 1.

[0134] Example 14

[0135] The present example provides a melt-blown nonwoven material, which is different from Example 1 only in that the heating rate to 100°C in the preparation method is 50°C / h, and the other steps and parameters are the same as those in Example 1.

[0136] Example 15

[0137] The present example provides a melt-blown non-woven material, which is only different from the example 1 in that, in the preparation method, no soaking in the cross-linking bath is performed, and direct temperature increase solidification is performed, and other steps and parameters are the same as those of the example 1.

[0138] Comparative examples 1 and 2

[0139] The comparative examples 1 and 2 each provide a melt-blown non-woven material, which is only different from the example 1 in that, in the preparation method, the phenolic resin is the phenolic resin provided in the comparative preparation examples 1 and 2, respectively, and other steps and parameters are the same as those of the example 1.

[0140] Comparative example 3

[0141] The present comparative example provides a melt-blown non-woven material, which is only different from the example 1 in that, in the preparation method, the phenolic resin used is obtained by polycondensation of phenol and formaldehyde, no modifier is added, the weight average molecular weight is 1355, the number average molecular weight is 897, and the molecular weight distribution index is 1.51, and other steps and parameters are the same as those of the example 1.

[0142] The structures of the melt-blown non-woven materials provided in the examples 1 to 15 and the comparative examples 1 to 3 are characterized, in which the main evaluation indexes of the structural characteristics are the grammage, the thickness, the fiber diameter, the pore size, and the porosity. The specific test results are shown in Table 2.

[0143] The grammage refers to the mass of the material per unit area, and is executed in accordance with GB / T 24218.1-2009 Textiles-Determination of mass per unit area. It should be noted that, since the melt-blown non-woven material prepared in the present application is mainly used in personal protection products, if the protective performance is simply improved by increasing the grammage, the heavier clothing will inevitably bring additional weight to the wearer, and therefore, the smaller the grammage is, the better it is under the premise of ensuring the thermal protection performance.

[0144] The thickness of the non-woven fabric also affects the balance between the thermal protection performance and the weight of the user. Unlike the traditional method of measuring the thickness of the material, since the non-woven fabric mostly has the characteristics of being fluffy and soft, the thickness of the non-woven material refers to the distance between the reference plate on which the non-woven material is placed and the presser foot which is parallel to the reference plate and exerts pressure on the non-woven material. In the present application, the thickness of the melt-blown non-woven material is executed in accordance with GB / T 24218.2-2009 Textiles-Determination of thickness, and the type of the non-woven material is classified as a fluffy non-woven material.

[0145] Fiber diameter: Because of the production characteristics of the melt-blown nonwoven fabric, the diameter of the fibers in the obtained web is mainly sub-micron. The test method first fixes the melt-blown fabric on the sample table using conductive glue, performs gold spraying treatment on the sample, uses a scanning electron microscope (SEM) to take pictures of the cross-section of the sample and saves the pictures. Using the Nano Measurer software, 100 different fibers in the above scanning electron microscope pictures are selected to calculate the average fiber diameter and fiber diameter distribution of the melt-blown nonwoven material.

[0146] Pore size: Nonwoven materials are typical three-dimensional porous materials, and the test method for pore size is the bubble point method. The test method refers to GB / T 32361-2015 Separation Membrane Pore Size Test Method Bubble Point and Average Flow Rate Method.

[0147] Porosity: The porosity determination method refers to the "mass-density" method in GB / T 42697-2023 Nonwoven Fabric Porosity Test Method. For single raw materials or nonwoven materials with known raw material ratios, the porosity of the nonwoven material can be indirectly calculated by testing the area density and thickness of the nonwoven material, the fiber density of various raw materials contained in the material, and the raw material ratio. The calculation formula is as follows:

[0148]

[0149] In the formula, n is the porosity (%), m is the mass per unit area of the nonwoven material (g / m 2 ), and p is the known fiber density of the nonwoven fabric (g / cm 3 ).

[0150] Table 2

[0151]

[0152] The properties of the melt-blown nonwoven materials provided in Examples 1-15 and Comparative Examples 1-3 were tested.

[0153] (1) Residual carbon rate: tested using a TG 209F3 thermogravimetric analyzer from Germany Netzsch. The temperature was raised to 800°C at a rate of 10°C / min, and the entire process was carried out in a nitrogen environment with a gas flow rate of 20 mL / min; the residual carbon rate directly represents the flame retardant performance of the melt-blown nonwoven material at high temperatures. The higher the residual carbon rate, the more components in the melt-blown nonwoven material become carbon fiber felt that is not flammable and does not melt after heating, which can continue to play a role in flame retardation and heat insulation.

[0154] (2) Thermal conductivity: According to the "transient plane heat source method" in ASTM D7984, each group of tests uses a TPS2500S thermal constant tester, selects a 7531 type probe, tests at 25°C ambient temperature, 3-5 times per group of tests, and takes the floating range and average value; the lower the thermal conductivity, the weaker the heat conduction ability of the material, that is, the better the heat insulation effect.

[0155] (3) Limiting oxygen index: according to GB / T 5454-1997 Textile Burning Performance Test Oxygen Index Method; high oxygen index indicates that the material is not easy to burn, low oxygen index indicates that the material is easy to burn, and generally, oxygen index <22% is considered flammable material, oxygen index between 22% and 27% is considered combustible material, and oxygen index >27% is considered difficult to burn material.

[0156] (4) Microcalorimetry: MCC-2 microcalorimeter is used for testing, and the temperature is raised to 750°C at a rate of 1°C / s during the test, and the peak value of the heat release peak is recorded.

[0157] (5) Thermal shrinkage: simulate the low radiant heat environment temperature during use by using an electric hot air oven, cut 3 pieces of 15cm*15cm pattern from the melt-blown non-woven material, place them at 200°C for 1h, and then measure the projected area again and calculate the thermal shrinkage, the calculation method is as follows:

[0158]

[0159] (6) Thermal infrared temperature: set the electric heating plate to 300°C, and place the melt-blown non-woven material directly on the electric heating plate for heating, use an infrared camera to observe the temperature change of its surface, when the surface temperature tends to be stable, record the average temperature and the highest temperature on the upper surface, which represents the heat insulation performance of the material; the lower the temperature, the better the heat insulation performance.

[0160] (7) Thermal protection performance: by simulating the fire scene environment on a small scale, the time required for heat to penetrate the measured sample to cause second-degree burns on human skin and the thermal protection coefficient value are determined, so as to evaluate the thermal protection performance of the sample. The larger the measured time value, the longer the time required to achieve second-degree skin burns; the larger the TPP value, the better the thermal protection performance of the measured sample. In the present application, the thermal protection performance test of the melt-blown non-woven material is carried out according to the standard ISO17492, and in the test, each sample is installed horizontally and directly exposed to the combination of convective and radiant heat sources. The intersection of the second-degree burn time curve and the total flow curve of the measured sample is used to judge its heat protection performance, and the calculation method of the TPP value is:

[0161] TPP = qt

[0162] wherein: TPP is the thermal protection capability value; q is the prescribed exposure heat flux, in cal / cm 2 s, which in this set of tests is 2.077 cal / cm 2 s; t is the time required for second-degree burns, in s.

[0163] The specific test results are shown in Table 3.

[0164] Table 3

[0165]

[0166]

[0167] From the data analysis of Table 1, it can be seen that the phenolic resin with specific molecular weight and molecular weight distribution and specific viscosity and melt index used in the present application has good spinnability and meets the performance requirements of the melt-blowing process for the material; and from Comparative Examples 1 and 2, it can be seen that the molecular weight and molecular weight distribution of the phenolic resin are not within the range defined in the present application, and the spinnability is slightly poor.

[0168] From the data in Tables 2 and 3, it can be seen that the melt-blown nonwoven material prepared using the specific phenolic resin has the characteristics of superfine fiber diameter, high porosity and small pore size; has excellent flame-retardant properties, thermal insulation properties and long service life characteristics; the melt-blown nonwoven material has low thermal shrinkage, high residual carbon rate and good thermal protection performance; the residual carbon rate of the melt-blown nonwoven material comprising the modified phenolic resin is > 60%, the thermal shrinkage is ≤ 2.3%, the TPP value is > 34 cal / cm 2 , the thermal conductivity coefficient is < 0.037 W·m -1 ·K -1 , and the limiting oxygen index is ≥ 31; and through further optimization, the present application can achieve the effects of residual carbon rate > 66%, thermal shrinkage ≤ 1.4%, TPP value > 36 cal / cm 2 , thermal conductivity coefficient < 0.035 W·m -1 ·K -1 , and limiting oxygen index ≥ 33.

[0169] From the comparison of Example 1 and Example 14, it can be seen that without pre-soaking, the fibers form a skin-core structure, which further changes after long-term heating, resulting in an increase in thermal shrinkage.

[0170] From Comparative Example 1, it can be seen that the molecular weight and molecular weight distribution of the phenolic resin are not within the range defined in the present application, and the residual carbon rate of the obtained nonwoven material is reduced, the thermal shrinkage is increased, the flame-retardant properties and thermal protection performance are both reduced, and the comprehensive performance is poor; among them, without boron modification, the thermal stability at the molecular chain level is poor, and more small molecules are cracked out and slightly shrink after long-term heating.

[0171] In the thermal protection performance test, the prepared material meets the requirements of "the TPP value of the overall thermal protection capability of the fire suit shall not be less than 28 cal / cm2" in the Chinese industry standard "XF 10-2014, firefighter protective clothing for fire fighting", and the performance can be obtained only by relying on a layer of phenolic resin melt-blown cloth, which further highlights the innovation and practicality of the present application. 2 , the secondary burn time is not less than 14 seconds", and this performance can be obtained only by relying on a layer of phenolic resin melt-blown cloth, which further highlights the innovation and practicality of the present application.

[0172] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A melt-blown nonwoven material characterized in that, The raw material of the melt-blown non-woven material comprises a phenolic resin; The weight average molecular weight of the phenolic resin is 1810-3000, and the number average molecular weight is 1270-2000; at 150°C, at a shear rate of 2500 s -1 under the conditions of a viscosity of 1 to 3 mPa.s and a melt index > 1000 g / 10 min. The ortho / para ratio of the phenolic resin is 1.1-3.89; The raw material of the phenolic resin comprises a modifier; The modifier is siloxane and boric acid; The siloxane is small molecule siloxane and polysiloxane, and the mass ratio of the small molecule siloxane to the polysiloxane is 1:(0.3-0.75); The preparation method of the melt-blown non-woven material comprises the following steps: The phenolic resin is melt-blown and cross-linked to obtain the melt-blown non-woven material; The cross-linking comprises the following steps: pre-soaking and temperature rising curing of the drawn fiber material in a cross-linking bath; The heating rate of the temperature rising is 1-20 ℃ / h.

2. The meltblown nonwoven material of claim 1, wherein, The viscosity of the phenolic resin is 2-3 mPa.s and the melt index is > 1500 g / 10 min at 150°C, at a shear rate of 2500 s -1 The viscosity of the phenolic resin is 2-3 mPa.s and the melt index is > 1500 g / 10 min at 150°C, at a shear rate of 2500 s 3. The meltblown nonwoven material of claim 1, wherein, The molecular weight distribution index of the phenolic resin is 1.32-1.

5.

4. The melt-blown nonwoven material according to claim 1, characterized in that The glass transition temperature of the phenolic resin is 80-100 ℃.

5. The melt-blown nonwoven material according to claim 1, characterized in that The raw material of the phenolic resin comprises a phenolic compound and an aldehyde compound.

6. The meltblown nonwoven material according to claim 5, wherein, The molar ratio of the phenolic compound to the aldehyde compound is 1:(0.7-0.85).

7. The melt-blown nonwoven material according to claim 1, characterized in that The mass of the siloxane is 3-12% based on 100% of the mass of the phenolic compound.

8. The melt-blown nonwoven material according to claim 1, characterized in that The small molecule siloxane comprises any one or a combination of at least two of dimethyldimethoxysilane, γ-aminopropyltriethoxysilane or γ-glycidyl ether propyltrimethoxysilane.

9. The melt-blown nonwoven material according to claim 1, characterized in that, The polysiloxane comprises polydimethylsiloxane.

10. The melt-blown nonwoven material according to claim 1, characterized in that, The mass of the boric acid is 3-9% based on 100% of the mass of the phenolic compound.

11. The melt-blown nonwoven material according to claim 5, characterized in that The phenolic resin is prepared by the following method, which comprises: The phenolic compound is subjected to polycondensation reaction with the aldehyde compound in the presence of a divalent metal salt to obtain the phenolic resin.

12. The meltblown nonwoven material of claim 11, wherein, The polycondensation reaction is performed at a pH value of 4-7, a temperature of 70-120 ℃ and a time of 0.5-1.5 h.

13. The melt-blown nonwoven material of claim 11, wherein, After the polycondensation reaction, the product obtained by the polycondensation reaction is further subjected to reaction with the modifier.

14. The meltblown nonwoven material according to claim 13, characterized in that, The step of reacting the product obtained by the polycondensation with the modifier comprises: reacting the product obtained by the polycondensation with siloxane to obtain siloxane modified phenolic resin; and then reacting the siloxane modified phenolic resin with boric acid to obtain the phenolic resin.

15. The meltblown nonwoven material according to claim 14, wherein, The product obtained by the polycondensation is reacted with the siloxane at a temperature of 70-120 ℃ and a time of 2-8 h.

16. The meltblown nonwoven material of claim 14, wherein, The siloxane modified phenolic resin is reacted with the boric acid at a pH value of 1-3, a temperature of 70-120 ℃ and a time of 1-3 h.

17. The meltblown nonwoven material of claim 1, wherein, The fiber diameter of the melt-blown non-woven material is 0.8-8 μm.

18. The melt-blown nonwoven material of claim 1, wherein, The porosity of the melt-blown non-woven material is >70%.

19. A process for making a melt-blown nonwoven material according to any one of claims 1 to 18, characterized in that, The preparation method comprises the following steps: The phenolic resin is melt-blown and cross-linked to obtain the melt-blown non-woven material; The cross-linking comprises the following steps: pre-soaking and temperature rising curing of the drawn fiber material in a cross-linking bath; The heating rate of the temperature rising is 1-20 ℃ / h.

20. The method of claim 19, wherein, The phenolic resin further comprises a step of drying at 60-120 ℃ for 2-8 h before melt-blown.

21. The method of claim 19, wherein, The melt temperature of the melt-blown is 100-165 ℃.

22. The preparation method according to claim 19, characterized in that, The hot air drawing temperature of the melt-blown is 120-200 ℃.

23. The method of claim 22, wherein, The receiving distance during the drawing is 25-50 cm.

24. The method of claim 19, wherein, The cross-linking bath for the cross-linking comprises a mixture of compound A and compound B; the compound A comprises any one or a combination of at least two of hydrochloric acid, phosphoric acid, oxalic acid or dilute sulfuric acid; the compound B comprises any one or a combination of at least two of formaldehyde, trioxane or hexamethylenetetramine.

25. The method of claim 24, wherein, The mass fraction of the compound A in the cross-linking bath is 10-25%, the mass fraction of the compound B is 10-25%, and the rest is water.

26. The method of claim 19, wherein, The temperature of the pre-soaking is room temperature, and the time is 0.5-2 h.

27. The preparation method according to claim 19, characterized in that, The temperature is raised to 100-120℃, and after the temperature is raised, the temperature is kept for 0.5-3 h.

28. The preparation method according to claim 19, characterized in that, The cross-linking further comprises a step of washing and drying.

29. The preparation method according to claim 19, characterized in that, The preparation method comprises the following steps: After the phenolic resin is dried at 60-120℃ for 2-8 h, melt-blowing is performed under the conditions that the temperature is 100-165℃, the hot air drawing temperature is 100-170℃, and the receiving distance during the drawing is 25-50 cm, to obtain a fiber material; the obtained fiber material is soaked in a cross-linking bath at room temperature for 0.5-2 h, then heated from room temperature to 100-120℃ at a heating rate of 1-20℃ / h and kept for 0.5-3 h, washed and dried, to obtain the melt-blowing non-woven material.

30. A thermal protection product, characterized by The material of the heat protection product comprises the melt-blowing non-woven material according to any one of claims 1-18.

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