阅读说明：本技术 一种无石棉密封垫片的制备方法 (Preparation method of asbestos-free sealing gasket ) 是由 黄昌俊 于 2020-04-20 设计创作，主要内容包括：本发明涉及一种无石棉密封垫片的制备方法,属于密封材料技术领域。本发明在制备的复合纤维中,聚合物分子链至少能以两种形式与蛭石硅酸盐片层结合,一是聚合物分子链以物理吸附的形式直接与硅酸盐内外表面结合在一起,二是通过蛭石硅酸盐片层间烷基胺(铵)分子与聚合物分子链“相容”,间接地与蛭石硅酸盐片层结合在一起；对于复合纤维而言,层状硅酸盐在聚合物基体中相当于“物理交联点”,该“物理交联点”与聚合物分子链“钉锚”在一起,使材料的冲击性能和弯曲性能得到改善；无石棉密封垫片中蛭石硅酸盐层片的离散程度越大,或片层间距越大,聚合物分子链与硅酸盐片层的结合几率也就越大,“物理交联点”也越多,因此增强增韧效果越好。(The invention relates to a preparation method of a non-asbestos sealing gasket, belonging to the technical field of sealing materials. In the prepared composite fiber, polymer molecular chains can be combined with vermiculite silicate sheets in at least two forms, wherein the polymer molecular chains are directly combined with the inner and outer surfaces of silicate in a physical adsorption form, and are indirectly combined with the vermiculite silicate sheets through the compatibility of alkylamine (ammonium) molecules among the vermiculite silicate sheets and the polymer molecular chains; for the composite fiber, the layered silicate is equivalent to a 'physical crosslinking point' in a polymer matrix, and the 'physical crosslinking point' is in anchor connection with a polymer molecular chain, so that the impact property and the bending property of the material are improved; the larger the dispersion degree of the vermiculite silicate lamina in the asbestos-free sealing gasket is, or the larger the lamina interval is, the larger the combination probability of the polymer molecular chain and the silicate lamina is, and the more the physical cross-linking points are, so that the better the reinforcing and toughening effect is.)

1. A preparation method of a non-asbestos sealing gasket is characterized by comprising the following concrete preparation steps:

(1) mixing vermiculite and phenolic resin, placing the mixture in a double-screw extruder, carrying out melt blending to obtain a melt, and placing the melt in an injector on an electrostatic spinning device for electrostatic spinning to obtain plain silk;

(2) soaking the cellulose filaments in the mixed solution, performing crosslinking curing, filtering to obtain cured fibers, washing the cured fibers with deionized water for 3-5 times, and naturally drying at room temperature to obtain composite fibers;

(3) taking composite fiber, carboxylic styrene-butadiene latex, sulfur, a vulcanization accelerator TMTD, zinc oxide and deionized water, mixing the composite fiber and the deionized water, placing the mixture in a pulping machine, pulping to obtain a suspension, adding the carboxylic styrene-butadiene latex, the sulfur, the vulcanization accelerator TMTD and the zinc oxide into the suspension, and stirring and mixing to obtain a mixed slurry;

(4) placing the mixed pulp into a paper sample copying device for copying into sheets to obtain wet paper, placing the wet paper in a flat vulcanizing machine, carrying out presulfurization treatment at normal pressure to obtain a semi-finished product, carrying out vulcanization treatment on the semi-finished product, and cooling to room temperature to obtain the asbestos-free sealing gasket.

2. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the melt blending step in the step (1) is as follows: mixing vermiculite and phenolic resin according to the mass ratio of 1: 5, placing the mixture into a double-screw extruder, and carrying out melt blending for 20-30 min at the temperature of 160-180 ℃ and the rotating speed of 100-120 r/min.

3. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the electrostatic spinning step in the step (1) is as follows: and (3) placing the melt into an injector on an electrostatic spinning device, and performing electrostatic spinning at the spinning temperature of 170-180 ℃, the spinning voltage of 40-45 kV and the receiving distance of 8-10 cm.

4. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the preparation steps of the mixed solution in the step (2) are as follows: and uniformly mixing the urotropine and the deionized water according to the mass ratio of 5: 8 to obtain a mixed solution.

5. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the crosslinking and curing step in the step (2) is as follows: and soaking the plain silk in the mixed solution, and placing the plain silk in a vacuum drying oven at the temperature of 60-70 ℃ for crosslinking and curing for 5-6 hours.

6. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the composite fiber, the carboxylic styrene-butadiene latex, the sulfur, the vulcanization accelerator TMTD, the zinc oxide and the deionized water in the step (3) are in the following proportion: respectively weighing 30-50 parts of composite fiber, 15-30 parts of carboxylic styrene-butadiene latex, 1-5 parts of sulfur, 1-3 parts of vulcanization accelerator TMTD, 1-3 parts of zinc oxide and 160-200 parts of deionized water according to parts by weight.

7. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the pulping treatment step in the step (3) is as follows: and mixing the composite fibers and deionized water, placing the mixture into a beating machine, and beating for 20-30 min at a beating speed of 230-300 r/min.

8. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the stirring and mixing step in the step (3) is as follows: adding carboxylic styrene-butadiene latex, sulfur, a vulcanization accelerator TMTD and zinc oxide into the suspension, and stirring and mixing for 25-30 min at the stirring speed of 150-200 r/min.

9. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the normal-pressure pre-vulcanization treatment step in the step (4) is as follows: and (3) placing the wet paper in a flat vulcanizing machine, and presulfurizing for 3-5 min at the temperature of 140-150 ℃ under normal pressure.

10. The method for preparing a asbestos-free sealing gasket according to claim 1, wherein: the vulcanization treatment step in the step (4) is as follows: and vulcanizing the semi-finished product for 10-15 min at the temperature of 150-160 ℃ and the pressure of 3-5 MPa.

Technical Field

The invention relates to a preparation method of a non-asbestos sealing gasket, belonging to the technical field of sealing materials.

Background

The sealing technology is a complex general technology closely combined with the material type, the design method and the manufacturing technology, and the leakage accidents of products and equipment are caused to happen frequently because the sealing technology is not taken into consideration for a long time. This not only results in energy waste, but also even serious events such as combustion and explosion. Major accidents due to seal failure occur almost every year around the world. The indian bopal event and the american challenger number crash, etc., frightened the world are pain trainings. Therefore, although the sealing device is small, the sealing performance is directly related to energy and environmental protection and personal safety.

The quality of the system seal is determined by the choice of sealing material, the structural design of the system and the manufacturing technique of the fitting. Where it is the choice of sealing material that can determine the life and reliability of the system seal. The sealing material is generally used for filling joint gaps, sealing joints, or encapsulating components, preventing leakage of internal media (gas, liquid, dust, and the like) or intrusion of external media, or preventing mechanical impact, vibration, and damage, thereby achieving sealing, insulating, heat insulating, and sound insulating effects, when installed in various joint areas of machinery, instruments, pipes, and the like. In a broad sense, sealing is used to seal a contact or gap with a material or device so that the medium does not leak. The sealing device or material can be pressed to deform or flow to wet and contact with the uneven surface of joint, gap, etc. to seal.

Asbestos rubber or latex sheets are currently common gasket materials. However, because asbestos is used as a reinforcing material, the problem of asbestos dust pollution in the links of production, use, installation, maintenance and the like is difficult to avoid. Since asbestos dust affects human health, the further development of asbestos rubber sealing materials is limited under the conditions that China is added to the world trade organization and the living standard of people is continuously improved. In recent years, research on asbestos-free sealing materials in China has been advanced to some extent. However, the common asbestos-free sealing material still uses organic solvents such as benzene or gasoline as the solvent of rubber, so that a large amount of harmful gas is generated in the production, the human health is damaged, the environment is polluted, and the production cost is increased. The method for preparing the sealing material by directly mixing and molding the rubber and the inorganic fiber in a dry method without a solvent has the problems of difficult uniform dispersion of the fiber and insufficient fiber opening. At present, the wet-process papermaking forming process which takes water as a solvent, latex as a binder and fibers such as brucite, sepiolite and the like as reinforcing materials improves the dispersion of the fibers. However, this method is a method of loosening the fibers in the production process of the asbestos latex sheet, i.e., a method of loosening the mineral fibers by mechanical grinding in an aqueous solution, and since the wear resistance of the mineral fibers such as sepiolite and brucite is far inferior to that of the asbestos fibers, the loss of fiber strength during grinding is large, and the reinforcing effect of the fibers cannot be fully exerted. Meanwhile, the product prepared by the wet process has poor water and oil resistance, and the application range is limited. Further, the fiber composite sealing material has problems such as poor self-lubricity and capillary leakage. In comparison, the flexible graphite sealing material has better comprehensive sealing performance. But the strength is lower, the manufacturing thickness is limited, and the brittle fracture and crushing are easy to generate during use. The price is generally higher than that of the fiber rubber plate. In addition, because the production raw material of the flexible graphite is acid used as an intercalation agent in the production of the expanded graphite, the flexible graphite sealing material generally has the problem that residual acid corrodes a sealing surface.

In recent 100 years, non-metallic gaskets developed are mainly made of non-metallic materials such as rubber, resin, polytetrafluoro ethylene and asbestos. The asbestos-containing non-metallic gasket shows excellent tensile strength, creep relaxation property, heat resistance, medium resistance and the like, and the performance of the prepared sealing gasket is particularly superior in high-temperature and high-pressure sealing occasions. However, during the production or use of asbestos-containing sealing gaskets, the asbestos breaks down into very fine fibrils, which pose a serious health hazard to humans. At the end of the twentieth century, the industrially developed countries have first sought a suitable asbestos-free fiber to replace asbestos, and the developed novel asbestos-free sealing gasket material has high strength, good rebound resilience and ultra-strong anti-permeability, and can be used as a good environment-friendly material for replacing asbestos gaskets at high temperature and high pressure.

The continuous development of human society promotes the synchronous progress of industrial civilization era and ecological civilization, advocates the creation of resource-saving, environment-friendly and low-carbon economic society, and becomes the main melody of the current era. Today, China is facing double target tasks of industrial development and ecological protection, and certain stricter environmental regulations can be issued to limit the use of asbestos products while industrial development is carried out. The sealing gasket is needed in the place where the fluid exists in the machinery, equipment and pipelines,

statistics show that 70% of catastrophic failures are related to improper use of the gasket seal. Therefore, the designed novel asbestos-free sealing gasket material has high strength, good rebound resilience and super-strong anti-permeability performance, and can replace the requirement of industrial development of a good environment-friendly material for asbestos gaskets at high pressure.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems of poor high temperature resistance and poor strength of the existing asbestos-free sealing material, the preparation method of the asbestos-free sealing gasket is provided.

In order to solve the technical problems, the invention adopts the following technical scheme:

(1) mixing vermiculite and phenolic resin, placing the mixture in a double-screw extruder, carrying out melt blending to obtain a melt, and placing the melt in an injector on an electrostatic spinning device for electrostatic spinning to obtain plain silk;

(2) soaking the cellulose filaments in the mixed solution, performing crosslinking curing, filtering to obtain cured fibers, washing the cured fibers with deionized water for 3-5 times, and naturally drying at room temperature to obtain composite fibers;

(3) taking composite fiber, carboxylic styrene-butadiene latex, sulfur, a vulcanization accelerator TMTD, zinc oxide and deionized water, mixing the composite fiber and the deionized water, placing the mixture in a pulping machine, pulping to obtain a suspension, adding the carboxylic styrene-butadiene latex, the sulfur, the vulcanization accelerator TMTD and the zinc oxide into the suspension, and stirring and mixing to obtain a mixed slurry;

(4) placing the mixed pulp into a paper sample copying device for copying into sheets to obtain wet paper, placing the wet paper in a flat vulcanizing machine, carrying out presulfurization treatment at normal pressure to obtain a semi-finished product, carrying out vulcanization treatment on the semi-finished product, and cooling to room temperature to obtain the asbestos-free sealing gasket.

The melt blending step in the step (1) is as follows: mixing vermiculite and phenolic resin according to the mass ratio of 1: 5, placing the mixture into a double-screw extruder, and carrying out melt blending for 20-30 min at the temperature of 160-180 ℃ and the rotating speed of 100-120 r/min.

The electrostatic spinning step in the step (1) is as follows: and (3) placing the melt into an injector on an electrostatic spinning device, and performing electrostatic spinning at the spinning temperature of 170-180 ℃, the spinning voltage of 40-45 kV and the receiving distance of 8-10 cm.

The preparation steps of the mixed solution in the step (2) are as follows: and uniformly mixing the urotropine and the deionized water according to the mass ratio of 5: 8 to obtain a mixed solution.

The crosslinking and curing step in the step (2) is as follows: and soaking the plain silk in the mixed solution, and placing the plain silk in a vacuum drying oven at the temperature of 60-70 ℃ for crosslinking and curing for 5-6 hours.

The composite fiber, the carboxylic styrene-butadiene latex, the sulfur, the vulcanization accelerator TMTD, the zinc oxide and the deionized water in the step (3) are in the following proportion: respectively weighing 30-50 parts of composite fiber, 15-30 parts of carboxylic styrene-butadiene latex, 1-5 parts of sulfur, 1-3 parts of vulcanization accelerator TMTD, 1-3 parts of zinc oxide and 160-200 parts of deionized water according to parts by weight.

The pulping treatment step in the step (3) is as follows: and mixing the composite fibers and deionized water, placing the mixture into a beating machine, and beating for 20-30 min at a beating speed of 230-300 r/min.

The stirring and mixing step in the step (3) is as follows: adding carboxylic styrene-butadiene latex, sulfur, a vulcanization accelerator TMTD and zinc oxide into the suspension, and stirring and mixing for 25-30 min at the stirring speed of 150-200 r/min.

The normal-pressure pre-vulcanization treatment step in the step (4) is as follows: and (3) placing the wet paper in a flat vulcanizing machine, and presulfurizing for 3-5 min at the temperature of 140-150 ℃ under normal pressure.

The vulcanization treatment step in the step (4) is as follows: and vulcanizing the semi-finished product for 10-15 min at the temperature of 150-160 ℃ and the pressure of 3-5 MPa.

Compared with other methods, the method has the beneficial technical effects that:

(1) melting and mixing vermiculite and phenolic resin, preparing composite phenolic fiber by adopting electrostatic spinning, pulping and dispersing the composite phenolic fiber, taking carboxylic styrene-butadiene latex as a binder, combining other accessory ingredients, and preparing an asbestos-free sealing gasket by adopting a copying process; in the prepared composite fiber, polymer molecular chains can be combined with vermiculite silicate sheets in at least two forms, wherein the polymer molecular chains are directly combined with the inner and outer surfaces of silicate in a physical adsorption form, and are indirectly combined with the vermiculite silicate sheets through the compatibility of alkylamine (ammonium) molecules among the vermiculite silicate sheets and the polymer molecular chains; it is these two binding domains that are both nanoscale squared, so their collective effect will be large; for composite fibers, the layered silicate is equivalent to 'physical crosslinking points' in a polymer matrix, and the 'physical crosslinking points' are in anchor connection with polymer molecular chains, so that when a system is acted by external force, the 'physical crosslinking points' are damaged and absorb energy, and the impact property and the bending property of the material are improved; the larger the dispersion degree of the vermiculite silicate lamina in the asbestos-free sealing gasket is, or the larger the lamina interval is, the larger the combination probability of the polymer molecular chain and the silicate lamina is, and the more the physical cross-linking points are, so that the better the reinforcing and toughening effect is;

(2) the vermiculite is a mineral silicate which can expand at high temperature and has expansibility; cation exchange and adsorption; the expanded vermiculite also has good water absorption; sound insulation; thermal insulation and fire resistance; freezing resistance; the chemical property of the expanded vermiculite is stable, so that the prepared asbestos-free sealing gasket has good high-temperature resistance;

(3) the phenolic fiber is a three-dimensional cross-linked flame-retardant organic fiber, contains about 76 percent of carbon, 18 percent of oxygen and 6 percent of hydrogen from the chemical composition, does not contain other elements, and is a non-crystalline and non-oriented three-dimensional structure polymer; the phenolic fiber has outstanding flame resistance, the LOI reaches 30 to 34 percent, and the phenolic fiber has self-extinguishing property, does not melt in flame and has less smoke; the original form can be kept during carbonization, and the carbonization rate is 50-60 percent; the sound insulation effect is good, the heat conductivity coefficient is small, and the gamma ray resistance is high; the carboxylic styrene-butadiene latex is latex prepared by emulsion copolymerization of butadiene and styrene, can be mixed with other latex in any proportion, has good adhesiveness and excellent diffusivity; the mechanical stability of the latex is superior to that of natural latex, and the latex has good water resistance, air tightness, excellent adhesive property and stability to chemical substances.

Detailed Description

Mixing vermiculite and phenolic resin according to a mass ratio of 1: 5, placing the mixture into a double-screw extruder, carrying out melt blending for 20-30 min at a temperature of 160-180 ℃ and a rotating speed of 100-120 r/min to obtain a melt, placing the melt into an injector on an electrostatic spinning device, and carrying out electrostatic spinning at a spinning temperature of 170-180 ℃, a spinning voltage of 40-45 kV and a receiving distance of 8-10 cm to obtain plain yarns; uniformly mixing urotropine and deionized water according to the mass ratio of 5: 8 to obtain a mixed solution, soaking the cellulose fibers in the mixed solution, placing the mixture in a vacuum drying oven at the temperature of 60-70 ℃ for crosslinking and curing for 5-6 h, filtering to obtain cured fibers, washing the cured fibers with the deionized water for 3-5 times, and naturally drying at room temperature to obtain composite fibers; respectively weighing 30-50 parts of composite fiber, 15-30 parts of carboxylic styrene-butadiene latex, 1-5 parts of sulfur, 1-3 parts of vulcanization accelerator TMTD, 1-3 parts of zinc oxide and 160-200 parts of deionized water according to parts by weight, mixing the composite fiber and the deionized water, placing the mixture in a beating machine, beating at the beating speed of 230-300 r/min for 20-30 min to obtain a suspension, adding the carboxylic styrene-butadiene latex, the sulfur, the vulcanization accelerator TMTD and the zinc oxide into the suspension, and stirring and mixing at the stirring speed of 150-200 r/min for 25-30 min to obtain a mixed slurry; placing the mixed slurry into a paper sample copying device to copy into sheets to obtain wet paper, placing the wet paper into a flat vulcanizing machine, pre-vulcanizing at the temperature of 140-150 ℃ and normal pressure for 3-5 min to obtain a semi-finished product, vulcanizing the semi-finished product at the temperature of 150-160 ℃ and the pressure of 3-5 MPa for 10-15 min, and cooling to room temperature to obtain the asbestos-free sealing gasket.