Filter material, and preparation method therefor and use thereof

Abstract

A filter material, and a preparation method therefor and the use thereof. The filter material comprises a first filter paper layer and a second filter paper layer, wherein the average pore diameter of the first filter paper layer is smaller than the average pore diameter of the second filter paper layer; the first filter paper layer contains first fiber components and a reinforcing agent; the fiber components include glass microfibers, alkali-free chopped strands and kapok fiber mercerized pulp; the second filter paper layer contains second fiber components and a reinforcing modifier; the second fiber components comprise the glass microfibers, the alkali-free chopped strands and chemical fibers; and the reinforcing modifier includes the reinforcing agent and a water and oil proofing agent. The filter material has a large oil absorption amount and high oil-gas separation efficiency.

Description

A filter material and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of filter materials, and in particular relates to a filter material and a preparation method and application thereof. Background Art

[0002] When a fuel engine is working, the high-pressure combustible mixture and burned gas in the cylinder combustion chamber will leak into the crankcase through the gap between the piston group and the cylinder. The accumulation of the oil-gas mixture will increase the crankcase pressure, causing more engine oil to enter the combustion chamber, further causing an increase in engine oil consumption and exhaust emissions, seriously affecting the service life of the engine and causing exhaust emissions to exceed the standard.

[0003] Currently, an oil-gas separator is generally added to the crankcase ventilation system to separate the oil droplets and gas in the oil-gas mixture. However, most of the filter materials used in existing oil-gas separators have problems such as low oil absorption capacity and low oil-gas separation efficiency.

[0004] Therefore, there is an urgent need to provide a filter material with large oil absorption capacity and high oil-gas separation efficiency.

[0005] Summary of the Invention

[0006] In response to the problems of low oil absorption and low oil-gas separation efficiency of filter materials in the existing technology, the present invention provides a filter material and its preparation method and application. The filter material provided by the present invention has large oil absorption and high oil-gas separation efficiency, which can meet the engine's requirements for oil-gas separation.

[0007] In a first aspect, the present invention provides a filter material, comprising a first filter paper layer and a second filter paper layer; the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer;

[0008] The first filter paper layer comprises a first fiber component and a reinforcing agent; the first fiber component comprises microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp;

[0009] The second filter paper layer comprises a second fiber component and a reinforcing modifier; the second fiber component comprises microfiber glass wool, alkali-free chopped strands and chemical fiber; the reinforcing modifier comprises a reinforcing agent and a water and oil repellent agent.

[0010] Preferably, the first filter paper layer comprises 90-96% of the first fiber component and 4-10% of the reinforcing agent by mass; the first fiber component comprises 55-70% of microfiber glass wool, 10-20% of alkali-free chopped strands and 20-25% of kapok fiber mercerized pulp by mass.

[0011] Preferably, the second filter paper layer contains 90-96% of the second fiber component and 4-10% of the reinforcing modifier by mass; the second fiber component contains 60-75% of microfiber glass wool, 10-20% of alkali-free chopped strands and 15-20% of chemical fiber by mass; the mass ratio of the reinforcing agent to the waterproof and oil-proof agent in the reinforcing modifier is 40:(1-5).

[0012] Preferably, the mass ratio of the first filter paper layer to the second filter paper layer is (1-2):1;

[0013] The average pore size of the first filter paper layer is 4 to 6 μm, and the average pore size of the second filter paper layer is 8 to 12 μm.

[0014] Preferably, the beating degree of the microfiber glass wool is 14-49°SR, and the diameter of the microfiber glass wool is 0.5-5 μm;

[0015] The diameter of the alkali-free chopped strands is 6 to 8 μm;

[0016] The kapok fiber mercerized pulp has a beating degree of 15 to 25°SR;

[0017] The chemical fiber is a bicomponent fiber, preferably a CO-PET / PET fiber.

[0018] In a second aspect, the present invention provides a method for preparing the filter material according to the first aspect, the method comprising the following steps:

[0019] S1. Dispersing microfiber glass wool, alkali-free chopped strands, and mercerized kapok fiber pulp in an acidic solution to obtain a first slurry, subjecting the first slurry to a first punching and screen application, and a first vacuum dehydration process to obtain a first wet paper web, and then subjecting the first wet paper web to a first reinforcement modification treatment using a reinforcement agent to obtain a first reinforced and modified wet paper web;

[0020] S2. Dispersing microfiber glass wool, alkali-free chopped strands, and chemical fibers in an acidic solution to obtain a second slurry, subjecting the second slurry to a second punching and screen application, and a second vacuum dehydration process to obtain a second wet paper web, and then subjecting the second wet paper web to a second reinforcing and modifying treatment using a reinforcing and modifying agent to obtain a second reinforced and modified wet paper web; the reinforcing and modifying agent comprising a reinforcing agent and a water and oil repellent agent;

[0021] S3. After the first enhanced modified wet paper web and the second enhanced modified wet paper web are laminated, a third vacuum dehydration forming process is performed to obtain a composite wet paper web;

[0022] S4. Drying and curing the composite wet paper web to obtain the filter material.

[0023] Preferably, the pH of the acidic solution is 2 to 3.5;

[0024] The sum of the mass of the microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp accounts for 0.5-1.5% of the total mass of the first pulp;

[0025] The total mass of the microfiber glass wool, alkali-free chopped strands and chemical fibers accounts for 0.5 to 1.5% of the total mass of the second slurry.

[0026] Preferably, the concentration of the first slurry on the screen is 0.05-0.15%;

[0027] The concentration of the second slurry on the screen is 0.1-0.2%; and / or

[0028] The vacuum degree of the first vacuum dehydration molding is greater than the vacuum degree of the second vacuum dehydration molding; preferably, the vacuum degree of the first vacuum dehydration molding is 0.025-0.03 MPa; the vacuum degree of the second vacuum dehydration molding is 0.02-0.025 MPa.

[0029] Preferably, the vacuum degree of the third vacuum dehydration molding is greater than the vacuum degree of the first vacuum dehydration molding; preferably, the vacuum degree of the third vacuum dehydration molding is 0.04 to 0.048 MPa; and / or

[0030] The drying and curing treatment includes a first-stage drying and curing treatment, a second-stage drying and curing treatment, and a third-stage drying and curing treatment; the temperature of the first-stage drying and curing treatment is 40-60°C, the temperature of the second-stage drying and curing treatment is 130-140°C, and the temperature of the third-stage drying and curing treatment is 150-160°C.

[0031] In a third aspect, the present invention provides use of the filter material described in the first aspect in oil-gas separation in an engine.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] The present invention improves the oil absorption capacity of the filter material by introducing mercerized kapok fiber pulp (kapok fiber that has been mercerized) with a hollow structure, smooth fiber surface, and strong oil adsorption into the first filter paper layer. A waterproof and oil-repellent agent is introduced into the second filter paper layer to improve the waterproof and oil-repellent properties of the filter material and effectively prevent secondary entrainment of oil droplets. The average pore size of the first filter paper layer is smaller than that of the second filter paper layer. When the oil-gas mixture enters the filter material through the pores of the first filter paper layer, it aggregates and grows larger, thereby better adsorbing oil droplets in the filter material. Simultaneously, the gradient structure with increased pore size increases the air permeability of the filter material, reduces filtration resistance, and facilitates gas permeation through the filter material. The filter material of the present invention has a high oil absorption capacity and high oil-gas separation efficiency, meeting the oil-gas separation requirements of engines. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] In a first aspect, the present invention provides a filter material, comprising a first filter paper layer and a second filter paper layer; the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer;

[0036] The first filter paper layer comprises a first fiber component and a reinforcing agent; the fiber component comprises microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp;

[0037] The second filter paper layer comprises a second fiber component and a reinforcing modifier; the second fiber component comprises microfiber glass wool, alkali-free chopped strands and chemical fiber; the reinforcing modifier comprises a reinforcing agent and a water and oil repellent agent.

[0038] It should be noted that during use of the filter material of the present invention, one side of the first filter paper layer serves as the inlet surface, and one side of the second filter paper layer serves as the outlet surface. The kapok fiber mercerized pulp of the present invention can be purchased directly or prepared in-house. The prepared kapok fiber mercerized pulp is obtained by mercerizing kapok fibers. Specifically, the kapok fiber mercerized pulp is obtained by soaking kapok fibers in a 1 mol / L NaOH solution at 50°C for 60 minutes, followed by washing and dehydration.

[0039] The present invention improves the oil absorption capacity of the filter material by introducing kapok fiber mercerized pulp (kapok fiber that has been mercerized) with a hollow structure, smooth fiber surface, and strong oil adsorption into the first filter paper layer; introducing a waterproof and oil-proof agent into the second filter paper layer to improve the waterproof and oil-proof properties of the filter material and effectively prevent the secondary entrainment of oil droplets; the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer, and when the oil-gas mixture enters the interior of the filter material through the pores of the first filter paper layer, it will gather and grow larger, so that the oil droplets can be better adsorbed in the filter material. At the same time, the gradient structure with increased pore size can increase the air permeability of the filter material, reduce the filtration resistance, and facilitate the permeation of gas through the filter material. The filter material of the present invention has a large oil absorption capacity and a high oil-gas separation efficiency, which can meet the oil-gas separation requirements of the engine. In addition, the surface of the kapok fiber mercerized pulp is smooth and the air permeability is good, which will not affect the filtration performance of the filter material.

[0040] According to some preferred embodiments, the first filter paper layer comprises 90-96% (for example, 90%, 91%, 92%, 93%, 94%, 95% or 96%) of the first fiber component by mass fraction and 4-10% (for example, 90%, 91%, 92%, 93%, 94%, 95% or 96%) of the reinforcing agent; the first fiber component comprises 55-70% (for example, 55%, 56%, 58%, 60%, 62%, 65%, 66%, 68% or 70%) of microfiber glass wool by mass fraction, 10-20% (for example, 10%, 12%, 14%, 16%, 18% or 20%) of alkali-free chopped strands, and 20-25% (for example, 20%, 21%, 22%, 23%, 24% or 25%) of kapok fiber mercerized pulp. The inventors have found that mercerized kapok fiber pulp within the above range is beneficial to the adsorption of oil. If the amount of mercerized kapok fiber pulp is too large, it will reduce the air permeability of the filter material, increase the filtration resistance of the filter material, and be detrimental to the permeation of gas.

[0041] According to some preferred embodiments, the second filter paper layer comprises 90-96% (for example, 90%, 91%, 92%, 93%, 94%, 95% or 96%) of the second fiber component by mass fraction and 4-10% (for example, 4%, 5%, 6%, 7%, 8%, 9% or 10%) of the reinforcing modifier; the second fiber component comprises 60-75% (for example, 60%, 62%, 64%, 65%, 66%, 68%, 70%, 71% or 72%) of the microfiber glass wool by mass fraction. 72%, 74% or 75%), alkali-free chopped strands 10-20% (for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%), and chemical fibers 15-20% (for example, 15%, 16%, 17%, 18%, 19% or 20%); the mass ratio of the reinforcing agent to the waterproof and oil-proofing agent in the reinforcing modifier is 40:(1-5) (for example, 40:1, 40:2, 40:3, 40:4 or 40:5).

[0042] In some preferred embodiments of the present invention, the reinforcing agent is one or more of phenolic resin, acrylic resin, and polyvinyl acetate resin; and the water- and oil-repellent agent is a fluorine-containing water- and oil-repellent agent. It should be noted that the reinforcing agent and water- and oil-repellent agent of the present invention are not limited to the aforementioned types.

[0043] In some preferred embodiments of the present invention, the microfiber glass wool comprises microfiber glass wool with low beating degree and microfiber glass wool with high beating degree; preferably, the microfiber glass wool comprises 475# microfiber glass wool with a beating degree of 14°SR and 475# microfiber glass wool with a beating degree of 49°SR; increasing the content of low beating degree microfiber glass wool is beneficial to obtaining a filter paper layer with a larger average pore size; therefore, the present invention preferably comprises the content of low beating degree microfiber glass wool in the first filter paper layer less than the content of low beating degree microfiber glass wool in the second filter paper layer.

[0044] According to some preferred embodiments, the mass ratio of the first filter paper layer to the second filter paper layer is (1-2):1 (for example, 1:1, 1.2:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1);

[0045] The average pore size of the first filter paper layer is 4 to 6 μm (for example, it can be 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm or 6 μm), and the average pore size of the second filter paper layer is 8 to 12 μm (for example, it can be 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm or 12 μm).

[0046] According to some preferred embodiments, the beating degree of the microfiber glass wool is 14-49°SR, and the diameter of the microfiber glass wool is 0.5-5 μm (for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm);

[0047] The diameter of the alkali-free chopped strands is 6 to 8 μm (for example, 6 μm, 6.2 μm, 6.4 μm, 6.5 μm, 6.6 μm, 7 μm, 7.2 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.8 μm or 8 μm);

[0048] The kapok fiber mercerized pulp has a beating degree of 15 to 25°SR;

[0049] The chemical fiber is a bicomponent fiber, preferably CO-PET / PET fiber. It should be noted that the skin structure of CO-PET / PET fiber is CO-PET with a melting point of 100-110°C, and the core structure is PET with a melting point of 250-280°C. The melting point of the skin layer of the fiber is lower than the curing temperature of the reinforcing agent and the reinforcing modifier. During the drying and curing process, the skin layer will melt and can act as a binder to better bond the microfiber glass wool and alkali-free chopped strands together to enhance the strength of the filter material. At the same time, the core layer has a high melting point and can also play a role in enhancing the strength of the filter material. The chemical fiber of the present invention is not limited to the above-mentioned bicomponent fiber, but can also be other chemical fibers, such as polyester fiber, aramid fiber, polytetrafluoroethylene fiber, and polyvinyl alcohol fiber.

[0050] In a second aspect, the present invention provides a method for preparing the filter material according to the first aspect, the method comprising the following steps:

[0051] S1. Dispersing microfiber glass wool, alkali-free chopped strands, and mercerized kapok fiber pulp in an acidic solution to obtain a first slurry, subjecting the first slurry to a first punching and screen application, and a first vacuum dehydration process to obtain a first wet paper web, and then subjecting the first wet paper web to a first reinforcement modification treatment using a reinforcement agent to obtain a first reinforced and modified wet paper web;

[0052] S2. Dispersing microfiber glass wool, alkali-free chopped strands, and chemical fibers in an acidic solution to obtain a second slurry, subjecting the second slurry to a second punching and screen application, and a second vacuum dehydration process to obtain a second wet paper web, and then subjecting the second wet paper web to a second reinforcing and modifying treatment using a reinforcing and modifying agent to obtain a second reinforced and modified wet paper web; the reinforcing and modifying agent comprising a reinforcing agent and a water and oil repellent agent;

[0053] S3. After the first enhanced modified wet paper web and the second enhanced modified wet paper web are laminated, a third vacuum dehydration forming process is performed to obtain a composite wet paper web;

[0054] S4. Drying and curing the composite wet paper web to obtain the filter material.

[0055] It should be noted that the first slurry and the second slurry of the present invention also include a deslagging step before being slurried and put on the screen; specifically: the first slurry and the second slurry are respectively diluted to control the deslagging concentration to be 0.4-0.6%, and then transported to the deslagging device for deslagging; wherein, the deslagging concentration of the first slurry refers to the mass fraction of microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp in the diluted slurry; the deslagging concentration of the second slurry refers to the mass fraction of microfiber glass wool, alkali-free chopped strands and chemical fiber in the diluted slurry; the reinforcing agent of the present invention is added in the form of an reinforcing agent solution, preferably, the mass ratio of the reinforcing agent to water in the reinforcing agent solution is 4:96; the waterproof and oil-proof agent is added in the form of a waterproof and oil-proof agent solution, preferably, the mass ratio of the waterproof and oil-proof agent to water in the waterproof and oil-proof agent solution is 3:97; the moisture content of the composite wet paper web is 65-70%.

[0056] The present invention comprises the following steps: dispersing microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp in an acidic solution to obtain a first slurry; subjecting the first slurry to a first punching and screen-mounting, and a first vacuum dehydration forming to obtain a first wet paper web; then using a reinforcing agent to perform a first reinforcing and modification treatment on the first wet paper web to obtain a first reinforced and modified wet paper web; dispersing microfiber glass wool, alkali-free chopped strands and chemical fiber in an acidic solution to obtain a second slurry; subjecting the second slurry to a second punching and screen-mounting, and a second vacuum dehydration forming to obtain a second wet paper web; then using a reinforcing agent and a waterproof and oil-proof agent to perform a second reinforcing and modification treatment on the second wet paper web to obtain a second reinforced and modified wet paper web; laminating the first reinforced and modified wet paper web and the second reinforced and modified wet paper web, and then performing a third vacuum dehydration forming to obtain a composite wet paper web; and finally drying and curing the composite wet paper web to obtain a filter material.

[0057] The present invention prepares a first reinforced modified wet paper web and a second reinforced modified wet paper web respectively, and then laminates the two and forms them through a third vacuum dehydration process to tightly interweave the two to obtain a composite wet paper web. No additional binder is required, and the filter material can be obtained through drying and curing.

[0058] The present invention prepares a filter material with an increased pore size gradient (the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer) by regulating and designing the microstructure of the filter material; introduces mercerized pulp of kapok fiber with a smooth fiber surface and strong oil adsorption capacity into the first filter paper layer to enhance the filter material's adsorption capacity for oil; the first filter paper layer (inflow surface) is enhanced and modified, and the second filter paper layer (outflow surface) is enhanced and modified to be waterproof and oil-proof; the waterproof and oil-proof properties of the second filter paper layer (outflow surface) can effectively prevent secondary entrainment of oil droplets.

[0059] The filter material of the present invention has good air permeability (greater than 75L / (m 2 ·s), large oil absorption capacity (greater than 2.8g / g) and high oil-gas separation efficiency (greater than 99.5%).

[0060] According to some preferred embodiments, the pH of the acidic solution is 2 to 3.5 (for example, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2 or 3.5);

[0061] The sum of the mass of the microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp accounts for 0.5-1.5% (for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%) of the total mass of the first slurry;

[0062] The sum of the masses of the microfiber glass wool, alkali-free chopped strands and chemical fibers accounts for 0.5 to 1.5% (for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%) of the total mass of the second slurry.

[0063] According to some preferred embodiments, the concentration of the first slurry on the screen is 0.05-0.15% (for example, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14% or 0.15%);

[0064] The concentration of the second slurry on the screen is 0.1-0.2% (for example, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.2%); and / or

[0065] The vacuum degree of the first vacuum dehydration molding is greater than the vacuum degree of the second vacuum dehydration molding; preferably, the vacuum degree of the first vacuum dehydration molding is 0.025~0.03MPa (for example, it can be 0.025MPa, 0.026MPa, 0.027MPa, 0.028MPa, 0.029MPa or 0.03MPa); the vacuum degree of the second vacuum dehydration molding is 0.02~0.025MPa (for example, it can be 0.02MPa, 0.021MPa, 0.022MPa, 0.023MPa, 0.024MPa or 0.025MPa).

[0066] The vacuum degree of the first vacuum dehydration molding of the present invention is greater than the vacuum degree of the second vacuum dehydration molding, which can ensure that the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer.

[0067] According to some preferred embodiments, the vacuum degree of the third vacuum dehydration forming is greater than the vacuum degree of the first vacuum dehydration forming; preferably, the vacuum degree of the third vacuum dehydration forming is 0.04-0.048 MPa (for example, it can be 0.04 MPa, 0.042 MPa, 0.044 MPa, 0.046 MPa or 0.048 MPa); the vacuum degree of the third vacuum dehydration forming of the present invention is greater than the vacuum degree of the first vacuum dehydration forming, which can ensure that the first reinforced modified wet paper web and the second reinforced modified wet paper web are tightly interwoven during the vacuum dehydration forming process.

[0068] The drying and curing treatment includes a first-stage drying and curing treatment, a second-stage drying and curing treatment, and a third-stage drying and curing treatment; the temperature of the first-stage drying and curing treatment is 40-60°C (for example, it can be 40°C, 42°C, 44°C, 45°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C), the temperature of the second-stage drying and curing treatment is 130-140°C (for example, it can be 130°C, 132°C, 134°C, 136°C, 138°C or 140°C), and the temperature of the third-stage drying and curing treatment is 150-160°C (for example, it can be 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C or 160°C). In order to ensure the comprehensive performance of the filter material, the drying and curing treatment adopts a three-stage contact drying and curing method. Preferably, the first stage of drying and curing treatment is carried out in a low-temperature drying cylinder at 40-60°C, the second stage of drying and curing treatment is carried out in a drying cylinder at 130-140°C, and the third stage of drying and curing treatment is carried out in a drying cylinder at 150-160°C. The drying and curing time of each stage is 40-60s; wherein, the use of a lower temperature in the first stage can effectively prevent the deformation of the reinforced composite wet paper web caused by excessive temperature; wherein the second and third stages are to ensure that the composite wet paper web is fully dried and the reinforcing agent and reinforcing modifier are fully cured, thereby enhancing the performance of the filter material.

[0069] In a third aspect, the present invention provides use of the filter material described in the first aspect in oil-gas separation in an engine.

[0070] The filter material provided by the present invention includes a first filter paper layer and a second filter paper layer with a stepped pore size increase; when in use, the first filter paper layer serves as the inlet surface, and the oil absorption capacity of the filter material is increased by introducing kapok fiber mercerized pulp (kapok fiber after mercerization treatment) with a hollow structure, a smooth fiber surface, and strong oil adsorption capacity into the first filter paper layer; the second filter paper layer contains a waterproof and oil-proof agent to improve the waterproof and oil-proof properties of the filter material and effectively prevent the secondary entrainment of oil droplets; when the oil-gas mixture enters the interior of the filter material through the pores of the first filter paper layer, it will gather and grow larger, and the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer, which can better adsorb oil droplets in the filter material. At the same time, the gradient structure with increased pore size can increase the air permeability of the filter material, reduce the filtration resistance, and facilitate the gas to pass through the filter material. In this way, oil and gas separation can be better achieved and the oil and gas separation efficiency of the filter material can be improved. The filter material of the present invention has a large oil absorption capacity and high oil and gas separation efficiency, which can meet the requirements of the engine for oil and gas separation.

[0071] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention is further described below with reference to embodiments.

[0072] It should be noted that the materials and reagents used in this invention can be purchased commercially or prepared in-house, with no specific restrictions on the type. Coniferous wood mercerized pulp can be purchased directly or prepared in-house. Homemade coniferous wood mercerized pulp is obtained by mercerizing coniferous wood; specifically, kapok fibers are soaked in a 1 mol / L NaOH solution at 50°C for 60 minutes, followed by washing and dehydration. The parts in the Examples and Comparative Examples are by mass.

[0073] Example 1

[0074] S1. Weigh the first fiber component: 56 parts of 475# microfiber glass wool with a beating degree of 14°SR, 15 parts of 475# microfiber glass wool with a beating degree of 49°SR, 14 parts of alkali-free short-cut shreds with a diameter of 7 μm, and 15 parts of kapok fiber mercerized pulp with a beating degree of 25°SR. First, put the alkali-free short-cut shreds and kapok fiber mercerized pulp into the pulper, and control the pH of the pulping white water to 3. Stir and disperse for 600 seconds. Then put the 475# microfiber glass wool into the pulper. The first paper web was subjected to a first reinforcement modification treatment using a reinforcing agent (acrylic resin emulsion) by overflow sizing, wherein the reinforcing agent was added in the form of a reinforcing agent solution (the mass ratio of the reinforcing agent to water was 4:96) to obtain a first reinforced and modified wet paper web;

[0075] S2. Weigh the second fiber component: 60 parts of 475# microfiber glass wool with a beating degree of 14°SR, 12 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm, and 15 parts of chemical fiber (CO-PET / PET fiber); first put the alkali-free short-cut strands and chemical fiber into the pulper, and control the pH of the pulping white water to 3, and stir and disperse for 420 seconds, then add 475# microfiber glass wool, and pulp for 300 seconds, and control low-consistency beating to obtain a second slurry with a concentration of 1.2%; the second slurry is subjected to pulping. a web having a web concentration of 0.2%, vacuum dehydration at 0.023 MPa to obtain a second wet paper web, and then performing a first reinforcing and modifying treatment on the first wet paper web by overflow sizing using a reinforcing agent (acrylic resin emulsion) and a waterproof and oil-proofing agent (C6 waterproof and oil-proofing agent), wherein the reinforcing agent is added in the form of a reinforcing agent solution (with a mass ratio of reinforcing agent to water of 4:96), and the waterproof and oil-proofing agent is added in the form of a waterproof and oil-proofing agent solution (with a mass ratio of waterproof and oil-proofing agent to water of 3:97), and the mass ratio of the reinforcing agent solution to the waterproof and oil-proofing agent solution is 10:1 to obtain a second reinforced and modified wet paper web;

[0076] S3. The first enhanced modified wet paper web and the second enhanced modified wet paper web are laminated and subjected to a third vacuum dehydration molding at 0.045 MPa to obtain a composite wet paper web having a moisture content of 65 to 70%;

[0077] S4. The composite wet paper web is sequentially subjected to a first-stage drying and curing treatment (low-temperature drying cylinder with a temperature of 40°C for 1 min), a second-stage drying and curing treatment (drying cylinder with a temperature of 140°C for 1 min), and a third-stage drying and curing treatment (drying cylinder with a temperature of 160°C for 1 min) to obtain a filter material comprising a first filter paper layer (with an average pore size of 4 to 6 μm) and a second filter paper layer (with an average pore size of 8 to 12 μm).

[0078] Example 2

[0079] Example 2 is basically the same as Example 1, except that in step S1, the first fiber component is: 53 parts of 475# microfiber glass wool with a beating degree of 14°SR and 14 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm and 20 parts of kapok fiber mercerized pulp with a beating degree of 25°SR.

[0080] Example 3

[0081] Example 3 is basically the same as Example 1, with the only difference being that in step S1, the first fiber component includes: 50 parts of 475# microfiber glass wool with a beating degree of 14°SR and 13 parts of 475# microfiber glass wool with a beating degree of 49°SR, 12 parts of alkali-free short-cut strands with a diameter of 7 μm, and 25 parts of kapok fiber mercerized pulp with a beating degree of 25°SR.

[0082] Example 4

[0083] Example 4 is substantially the same as Example 1, except that, in step S1, the first fiber component includes 53 parts of 475# microfiber glass wool with a beating degree of 14°SR, 14 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free chopped strands with a diameter of 7 μm, and 20 parts of kapok fiber mercerized pulp with a beating degree of 25°SR.

[0084] In step S2, the mass ratio of the waterproof and oil-proofing agent to water in the waterproof and oil-proofing agent solution is 5:97.

[0085] Comparative Example 1

[0086] Comparative Example 1 is basically the same as Example 1, except that in step S1, the first fiber component includes 66 parts of 475# microfiber glass wool with a beating degree of 14°SR, 18 parts of 475# microfiber glass wool with a beating degree of 49°SR, and 16 parts of alkali-free chopped strands with a diameter of 7 μm.

[0087] Comparative Example 2

[0088] Comparative Example 2 is substantially the same as Example 1, except that in step S1, the first fiber component includes 66 parts of 475# microfiber glass wool with a beating degree of 14° SR, 18 parts of 475# microfiber glass wool with a beating degree of 49° SR, and 16 parts of alkali-free chopped strands with a diameter of 7 μm.

[0089] In step S2, the second fiber components include: 66 parts of 475# microfiber glass wool with a beating degree of 14°SR, 18 parts of 475# microfiber glass wool with a beating degree of 49°SR, and 16 parts of alkali-free chopped strands with a diameter of 7 μm.

[0090] Comparative Example 3

[0091] Comparative Example 3 is substantially the same as Example 2, except that no water- and oil-repellent solution is added in step S2.

[0092] Comparative Example 4

[0093] Comparative Example 4 is basically the same as Example 2, except that in step S2, the second fiber component includes: 53 parts of 475# microfiber glass wool with a beating degree of 14° SR, 14 parts of 475# microfiber glass wool with a beating degree of 49° SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm, and 20 parts of kapok fiber mercerized pulp with a beating degree of 25° SR.

[0094] Comparative Example 5

[0095] Comparative Example 5 is substantially the same as Example 2, except that in step S1, the first fiber component includes: 60 parts of 475# microfiber glass wool with a beating degree of 14° SR, 12 parts of 475# microfiber glass wool with a beating degree of 49° SR, 13 parts of alkali-free chopped strands with a diameter of 7 μm, and 15 parts of chemical fiber;

[0096] In step S2, the mass fractions of the second fiber component are: 53 parts of 475# microfiber glass wool with a beating degree of 14°SR, 14 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm and 20 parts of kapok fiber mercerized pulp with a beating degree of 25°SR.

[0097] Comparative Example 6

[0098] Comparative Example 6 is basically the same as Example 2, except that: in step S1, the first fiber component: 53 parts of 475# microfiber glass wool with a beating degree of 14°SR and 14 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm and 20 parts of kapok fiber (unmercerized).

[0099] Comparative Example 7

[0100] Comparative Example 7 is basically the same as Example 2, except that: the first fiber component is: 53 parts of 475# microfiber glass wool with a beating degree of 14°SR and 14 parts of 475# microfiber glass wool with a beating degree of 49°SR, 13 parts of alkali-free short-cut strands with a diameter of 7 μm and 20 parts of softwood mercerized pulp with a beating degree of 25°SR.

[0101] Comparative Example 8

[0102] Comparative Example 8 is basically the same as Example 2, except that the mass fractions of the first fiber component are 46 parts of 475# microfiber glass wool with a beating degree of 14°SR, 12.5 parts of 475# microfiber glass wool with a beating degree of 49°SR, 11.5 parts of alkali-free short-cut strands with a diameter of 7 μm, and 30 parts of kapok fiber mercerized pulp with a beating degree of 25°SR.

[0103] Table 1. Performance data of filter materials obtained in Examples and Comparative Examples

[0104] It should be noted that in Table 1, the test standard for air permeability refers to GB / T5453; the test standard for oil-water separation efficiency refers to ISO 12500-1:2007; and liquid absorption (g / g) = oil mass (g) / filter paper mass (g).

[0105] As shown in Table 1, the filter materials prepared in Examples 1-4 of the present invention have good air permeability (greater than 75L / (m 2·s), with a large oil absorption capacity (greater than 2.8g / g) and a high oil-gas separation efficiency (greater than 99.5%), effectively avoiding the secondary entrainment of oil droplets in the gas. Comparative Example 1 shows that the first filter paper layer does not contain mercerized kapok fiber pulp, and the resulting filter material has a significantly lower liquid absorption capacity. Comparative Example 2 shows that the first filter paper layer (inflow surface) and the second filter paper layer (outflow surface) do not contain mercerized kapok fiber pulp and have no gradient microstructure (the two layers have the same composition). Compared with the gradient microstructure of Comparative Example 1, the air permeability and liquid absorption of the filter material are significantly reduced. Comparative Example 3 does not contain any waterproof and oil-proofing agent. Compared with Example 2, the filter material has an increased liquid absorption capacity, but the oil-gas separation efficiency is significantly reduced, and the secondary entrainment of oil droplets occurs, which will pollute the engine operating environment. In Comparative Example 4, both the first and second filter paper layers contained mercerized kapok fiber pulp and had a non-gradient microstructure (the two layers had the same composition). Compared to Examples 2 and 4, the filter material produced in Comparative Example 4 exhibited increased liquid absorption, but significantly decreased oil-gas separation efficiency. Comparative Example 5 differed from Example 2 only in that the fiber components of the first and second filter paper layers were interchanged. The resulting filter material exhibited significantly lower liquid absorption, air permeability, and oil-gas separation efficiency compared to Example 2. Compared to Example 2, the filter material produced in Comparative Example 6, which used unmercerized kapok fiber, exhibited significantly lower air permeability, liquid absorption, and oil-gas separation efficiency. Compared to Example 2, the filter material produced in Comparative Example 7, which used mercerized conifer pulp due to its lack of hollow structure, exhibited significantly lower air permeability and liquid absorption, as well as lower oil-gas separation efficiency. Compared to Example 2, the mass fraction of mercerized kapok fiber pulp in the first fiber component in Comparative Example 8 was too high, significantly reducing the filter material's air permeability and hindering gas permeation.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A filter material, characterized in that: The filter material comprises a first filter paper layer and a second filter paper layer; the average pore size of the first filter paper layer is smaller than the average pore size of the second filter paper layer; The first filter paper layer comprises a first fiber component and a reinforcing agent; The first fiber component comprises microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp; The second filter paper layer comprises a second fiber component and a reinforcing modifier; The second fiber component comprises microfiber glass wool, alkali-free chopped strands and chemical fibers; The reinforcing modifier comprises a reinforcing agent and a water and oil repellent agent.

2. The filter material according to claim 1, characterized in that The first filter paper layer comprises 90-96% of the first fiber component and 4-10% of the reinforcing agent by mass fraction; the first fiber component comprises 55-70% of microfiber glass wool, 10-20% of alkali-free chopped strands and 20-25% of kapok fiber mercerized pulp by mass fraction.

3. The filter material according to claim 1, characterized in that The second filter paper layer contains 90-96% of the second fiber component and 4-10% of the reinforcing modifier by mass fraction; the second fiber component contains 60-75% of microfiber glass wool, 10-20% of alkali-free chopped strands and 15-20% of chemical fiber by mass fraction; the mass ratio of the reinforcing agent to the waterproof and oil-proofing agent in the reinforcing modifier is 40:(1-5).

4. The filter material according to claim 1, characterized in that: The mass ratio of the first filter paper layer to the second filter paper layer is (1-2):1; The average pore size of the first filter paper layer is 4-6 μm, and the average pore size of the second filter paper layer is 8-12 μm.

5. The filter material according to claim 1, characterized in that: The beating degree of the microfiber glass wool is 14-49°SR, and the diameter of the microfiber glass wool is 0.5-5 μm; The diameter of the alkali-free chopped strands is 6 to 8 μm; The kapok fiber mercerized pulp has a beating degree of 15-25°SR; The chemical fiber is a bicomponent fiber.

6. The filter material according to claim 5, characterized in that The chemical fiber is CO-PET / PET fiber.

7. A method for preparing the filter material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1. dispersing microfiber glass wool, alkali-free short strands and kapok fiber mercerized pulp in an acidic solution to obtain a first slurry, subjecting the first slurry to a first pulping and screen-mounting, a first vacuum dehydration and forming process to obtain a first wet paper web, and then subjecting the first wet paper web to a first reinforcing and modifying process using a reinforcing agent to obtain a first reinforced and modified wet paper web; S2. dispersing microfiber glass wool, alkali-free chopped strands and chemical fibers in an acidic solution to obtain a second slurry, subjecting the second slurry to a second slurry punching and screen-mounting, and a second vacuum dehydration forming to obtain a second wet paper web, and then subjecting the second wet paper web to a second reinforcing and modifying treatment with a reinforcing modifier to obtain a second reinforcing and modified wet paper web; The reinforcing modifier comprises a reinforcing agent and a water and oil repellent agent; S3. After laminating the first enhanced modified wet paper web and the second enhanced modified wet paper web, performing a third vacuum dehydration forming to obtain a composite wet paper web; S4. Drying and curing the composite wet paper web to obtain the filter material.

8. The preparation method according to claim 7, characterized in that: The pH of the acidic solution is 2 to 3.5; The sum of the mass of the microfiber glass wool, alkali-free chopped strands and kapok fiber mercerized pulp accounts for 0.5-1.5% of the total mass of the first pulp; The sum of the mass of the microfiber glass wool, alkali-free chopped strands and chemical fibers accounts for 0.5-1.5% of the total mass of the second slurry.

9. The preparation method according to claim 7, characterized in that: The concentration of the first slurry on the Internet is 0.05-0.15%; The concentration of the second slurry on the screen is 0.1-0.2%; and / or The vacuum degree of the first vacuum dehydration molding is greater than the vacuum degree of the second vacuum dehydration molding.

10. The preparation method according to claim 9, characterized in that: The vacuum degree of the first vacuum dehydration molding is 0.025-0.03 MPa; the vacuum degree of the second vacuum dehydration molding is 0.02-0.025 MPa.

11. The preparation method according to claim 7, characterized in that: The vacuum degree of the third vacuum dehydration molding is greater than the vacuum degree of the first vacuum dehydration molding; and / or The drying and curing treatment includes a first stage drying and curing treatment, a second stage drying and curing treatment and a third stage drying and curing treatment; the temperature of the first stage drying and curing treatment is 40-60°C, the temperature of the second stage drying and curing treatment is 130-140°C, and the temperature of the third stage drying and curing treatment is 150-160°C.

12. The preparation method according to claim 11, characterized in that: The vacuum degree of the third vacuum dehydration molding is 0.04-0.048 MPa.

13. Use of the filter material according to any one of claims 1 to 6 in oil-gas separation of an engine.

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