A polyethylene sheet material

Abstract

The present invention relates to a polyethylene sheet material, the raw material of which is mainly polyethylene particles, the gram weight of the polyethylene sheet material is more than 40g / square meter, and the BET specific area is 9m 2 / gm or more; the mass fraction of polyethylene particles in the polyethylene sheet material is more than 80%; the raw materials also include polyethylene homologues, polypropylene, polyolefins, polybutene-1, poly(4-methyl-1-pentene), polyvinylidene fluoride, or more. The present application has good performance and a wide range of applications.

Description

[Technical field]

[0001] The invention relates to the field of textile technology, in particular to a polyethylene sheet material. [Background technology]

[0002] Flash spinning, also known as flash evaporation, flash spinning or rapid spinning, instant solvent volatilization into a web method, does not use melt spinning, but uses dry spinning technology. That is, the polymer is dissolved in a certain solvent to make a spinning solution, and then sprayed out from the spinneret. Due to the rapid volatilization of the solvent, the polymer is re-solidified into fibers. At the same time, the dry spinning technology used in the flash evaporation method is different from the ordinary dry spinning, mainly reflected in the flash evaporation process using a lower spinning solution viscosity, and sprayed out from the spinneret at extremely high pressure and speed. Due to the low viscosity and good fluidity of the solution, the liquid filaments solidify in high-speed motion to form extremely fine fiber filaments, and are finally adsorbed on the web curtain to directly form a fiber web.

[0003] Flash-steamed polyethylene non-woven fabrics have many excellent properties: the polyethylene non-woven fabrics produced by this method have excellent waterproof and breathable properties; the sheets have excellent strength, tear resistance, puncture resistance, and bursting resistance; the sheets generally do not fuzz or generate dust; they have excellent performance in a wide temperature range, etc. Due to the above excellent properties, flash-steamed polyethylene non-woven fabrics are widely used in packaging materials, protective clothing, cover cloths, and printing substrates.

[0004] Since the flash evaporation method uses solvent to dissolve the polymer, the tail gas contains solvent, so the post-treatment of the tail gas is more critical. At present, the solvent in the conventional tail gas is often recovered by adsorption and desorption. Common adsorbents include: activated carbon (granular or honeycomb), granular molecular sieve, activated carbon fiber. These adsorbents have a characteristic that they are all solid. Because of the solid characteristics of the adsorbent, the recovery process is basically: solid. Because of the solid characteristics of the adsorbent, the recovery process is basically: low-temperature adsorption and high-temperature desorption. The disadvantages of the above process are: (1) Solid adsorbents are difficult to flow, so different equipment needs to be switched to implement adsorption and desorption; (2) The adsorption capacity of the adsorbent is low, so a large amount of adsorbent is required, resulting in a large adsorption equipment. (3) At the same time, the solvent after adsorption cannot be recovered and reused. [Summary of the invention]

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a polyethylene sheet material.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A polyethylene sheet material, the raw material is mainly polyethylene particles, the gram weight of the polyethylene sheet material is more than 40g / square meter, and the BET specific area is 9m 2 / gm or more.

[0008] The mass fraction of the polyethylene particles in the polyethylene sheet material is more than 80%.

[0009] The mass fraction of the polyethylene particles in the polyethylene sheet material is more than 90%.

[0010] The BET specific area is 12m 2 / gm or more.

[0011] The BET specific area is 18m 2 / gm or more.

[0012] The BET specific area is 24m 2 / gm or more.

[0013] The BET specific area is 30m 2 / gm or less.

[0014] The raw materials also include one or more of polyethylene homologues, polypropylene, polyolefins, polybutene-1, poly(4-methyl-1-pentene), and polyvinylidene fluoride.

[0015] A method for processing a polyethylene sheet material comprises the following steps:

[0016] (1) preparing a spinning solution, adding a solvent into a reaction kettle, and then adding a polymer into the solvent to dissolve it to obtain a spinning solution;

[0017] (2) spinning, using the spinning solution obtained in step 1 to spin by flash evaporation to obtain polyethylene flash fibers; and obtaining polyethylene sheet materials by hot pressing;

[0018] (3) tail gas adsorption, the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and polyethylene glycol diethyl ether for adsorbing solvent vapor is sprayed from the upper section of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower, and the gas is discharged from the top of the adsorption tower.

[0019] The polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0020] In the spinning solution, the mass fraction of the polymer is 12-22%.

[0021] The spinning temperature is 200-220°C.

[0022] The solvent includes trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane, 1,2-dichloro-1,2,2-trifluoroethane, 1,1-dichloro-2,2-difluoroethane, 1,2-dichloro-1,1-difluoroethane and 1,1-dichloro-1-fluoroethane, 1,1,1,2-tetrafluoroethane (HC-134a), 1,1-difluoroethane (HC-152a), 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3,3,4,4-octafluorobutane, 1,1,1,3,3-pentafluorobutane, 2,3-dihydrodecafluoropentane, 1H,6H-perfluorohexane, 1H-perfluoroheptane, 1H-perfluorohexane or one or more thereof; and may also be isomers or analogs thereof.

[0023] The residence time of the solvent vapor in the adsorption tower is 5 to 25 seconds.

[0024] The temperature of the polyethylene glycol diethyl ether is 10-30°C, preferably 15-25°C.

[0025] The processing method of the polyethylene sheet material comprises the following steps:

[0026] (4) The adsorbed liquid discharged from the bottom of the adsorption tower is transported to the heat exchanger through the first delivery pump for heat exchange and temperature increase;

[0027] (5) The liquid after heat exchange is heated to 70-190° C. by the first heater, transported to the upper section of the desorption tower, and sprayed into the desorption tower from the upper section of the desorption tower for desorption. The temperature in the desorption tower is 50-210° C. and the pressure is below 5 KPa;

[0028] (6): After desorption, the analyzed liquid is discharged from the bottom of the desorption tower and transported to the heat exchanger by the second delivery pump, where it undergoes heat exchange with the adsorbed liquid in the heat exchanger and is cooled to 0-40°C by the cooler before entering the adsorption tower;

[0029] (7): The analyzed gas is discharged from the top of the analysis tower into the condenser, and the condensate obtained after condensation is stored in a recovery tank.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) The present application uses polyethylene glycol diethyl ether liquid adsorbent and the exhaust gas to be absorbed in countercurrent to achieve adsorption of solvent vapor in the exhaust gas. Compared with the method of using solid adsorbent in the prior art, the entire process operation is simpler and the production cost is reduced.

[0032] (2) The present application uses polyethylene glycol diethyl ether as an adsorbent. The polyethylene glycol diethyl ether is alkyl-terminated, relatively inert, non-reactive, and has good thermal stability, thereby providing thermal stability and chemical stability. The polyethylene glycol structure can provide high solubility and can dissolve various halogenated hydrocarbons, providing a basis for physical adsorption. At the same time, polyethylene glycol diethyl ether has a high boiling point, and halogenated hydrocarbons can be simply and conveniently desorbed by heating, while the loss rate of polyethylene glycol diethyl ether itself is low.

[0033] (3) In the tail gas treatment process of the present application, both materials and heat can be recycled, which is energy-saving and environmentally friendly.

Brief Description of the Drawings

[0034] Figure 1 A schematic diagram of the structure of this application;

[0035] Markings in the attached drawings:

[0036] 1 adsorption tower,

[0037] 2 The first delivery pump,

[0038] 3 heat exchangers,

[0039] 4 first heater,

[0040] 5 analytical towers,

[0041] 6 condenser,

[0042] 7 recovery tanks,

[0043] 8 Second delivery pump,

[0044] 9 Cooler. [Specific implementation method]

[0045] A specific embodiment of a polyethylene sheet material of the present invention is provided below.

[0046] Example 1

[0047] A method for processing a polyethylene sheet material comprises the following steps:

[0048] (1) preparing a spinning solution, adding a solvent into a reaction kettle, and then adding a polymer into the solvent to dissolve it to obtain a spinning solution;

[0049] The polymer is polyethylene particles;

[0050] The solvent is 1,1-dichloro-2,2,2-trifluoroethane and 1,1,2,2,3,3,4,4-octafluorobutane; the volume ratio of the two is 7:3;

[0051] (2) spinning, using the spinning solution obtained in step 1 to spin by flash evaporation to obtain polyethylene flash fibers; and obtaining polyethylene sheet materials by hot pressing;

[0052] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 61 mg / m 3 ;

[0053] In the spinning solution, the mass fraction of the polymer is 15%.

[0054] The residence time of the solvent vapor in the adsorption tower is 5 seconds.

[0055] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0056] (4) The adsorbed liquid discharged from the bottom of the adsorption tower 1 is transported to the heat exchanger 3 through the first delivery pump 2 for heat exchange and temperature increase;

[0057] (5) The liquid after heat exchange is heated to 70-190°C by the first heater 4, transported to the upper section of the desorption tower, and sprayed into the desorption tower from the upper section of the desorption tower 5 for desorption. The temperature in the desorption tower is 50-210°C and the pressure is below 5KPa;

[0058] (6): After desorption, the analyzed liquid is discharged from the bottom of the desorption tower and transported to the heat exchanger by the second delivery pump 8, where it undergoes heat exchange with the adsorbed liquid in the heat exchanger and is cooled to 0-40°C by the cooler 9 before entering the adsorption tower;

[0059] (7): The gas after analysis is discharged from the top of the analysis tower to the condenser 6, and the condensate obtained after condensation is stored in the recovery tank 7.

[0060] The polyethylene sheet material prepared in this embodiment has a gram weight of 42 g / m2 and a BET specific area of ​​15.3 m 2 / gm. The BET specific area is tested by the BET specific area tester of Bester Company.

[0061] Example 2

[0062] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0063] The only difference is that in step (3),

[0064] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 55 mg / m 3 ;

[0065] In the spinning solution, the mass fraction of the polymer is 15%.

[0066] The residence time of the solvent vapor in the adsorption tower is 10 seconds.

[0067] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0068] The polyethylene sheet material prepared in this embodiment has a gram weight of 43.4 g / m2 and a BET specific area of ​​15.8 m 2 / gm.

[0069] Example 3

[0070] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0071] The only difference is that in step (3),

[0072] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 49 mg / m 3 ;

[0073] In the spinning solution, the mass fraction of the polymer is 15%.

[0074] The residence time of the solvent vapor in the adsorption tower is 15 seconds.

[0075] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0076] The polyethylene sheet material prepared in this embodiment has a gram weight of 43.9 g / m2 and a BET specific area of ​​16.5 m 2 / gm.

[0077] Example 4

[0078] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0079] The only difference is that in step (3),

[0080] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 46 mg / m 3 ;

[0081] In the spinning solution, the mass fraction of the polymer is 15%.

[0082] The residence time of the solvent vapor in the adsorption tower is 20 seconds.

[0083] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0084] The polyethylene sheet material prepared in this embodiment has a gram weight of 42.9 g / m2 and a BET specific area of ​​15.5 m 2 / gm.

[0085] Example 5

[0086] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0087] The only difference is that in step (3),

[0088] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled gas is 43 mg / m 3 ;

[0089] In the spinning solution, the mass fraction of the polymer is 15%.

[0090] The residence time of the solvent vapor in the adsorption tower is 25 seconds.

[0091] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0092] The polyethylene sheet material prepared in this embodiment has a gram weight of 43.1 g / m2 and a BET specific area of ​​15.9 m 2 / gm.

[0093] Example 6

[0094] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0095] The only difference is that in step (3),

[0096] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 42 mg / m 3 ;

[0097] In the spinning solution, the mass fraction of the polymer is 15%.

[0098] The residence time of the solvent vapor in the adsorption tower is 30 seconds.

[0099] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0100] The polyethylene sheet material prepared in this embodiment has a gram weight of 41.9 g / m2 and a BET specific area of ​​14.2 m 2 / gm.

[0101] Example 7

[0102] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0103] The only difference is that in step (3),

[0104] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 41 mg / m 3 ;

[0105] In the spinning solution, the mass fraction of the polymer is 15%.

[0106] The residence time of the solvent vapor in the adsorption tower is 35 seconds.

[0107] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0108] The polyethylene sheet material prepared in this embodiment has a gram weight of 43.5 g / m2 and a BET specific area of ​​16.2 m 2 / gm.

[0109] Example 8

[0110] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0111] The only difference is that in step (3),

[0112] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 2.132 g / m 3 ;

[0113] In the spinning solution, the mass fraction of the polymer is 15%.

[0114] The residence time of the solvent vapor in the adsorption tower is 2 seconds.

[0115] The temperature of the polyethylene glycol diethyl ether is 20°C.

[0116] As can be seen from Examples 1-8, the time is too short to be less than 5 seconds, which is not conducive to the adsorption. However, as the residence time is extended (more than 20 seconds), the adsorption effect reaches a balance, that is, no longer changes significantly. The control of this adsorption time is one of the technical points of this application. Generally speaking, the adsorption time is so short as 5-30 seconds, and the adsorption effect is generally poor. This application mainly uses polyethylene glycol diethyl ether as an adsorbent. The polyethylene glycol diethyl ether alkyl end-capping is relatively inert, non-reactive, and has good thermal stability, so that thermal stability and chemical stability can be provided; the polyethylene glycol structure can provide high solubility, can dissolve various halogenated hydrocarbons, and provide a basis for physical adsorption. At the same time, polyethylene glycol diethyl ether has a higher boiling point, and halogenated hydrocarbons can be simply and conveniently desorbed by heating. Mainly due to the structural characteristics, it has a very high adsorption effect, which is an efficiency that conventional solid adsorbents cannot achieve.

[0117] The polyethylene sheet material prepared in this embodiment has a gram weight of 41.9 g / m2 and a BET specific area of ​​18.5 m 2 / gm.

[0118] Example 9

[0119] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0120] The only difference is that in step (3),

[0121] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 40 mg / m 3 .

[0122] In the spinning solution, the mass fraction of the polymer is 15%.

[0123] The residence time of the solvent vapor in the adsorption tower is 15 seconds.

[0124] The temperature of the polyethylene glycol diethyl ether is 10°C.

[0125] The polyethylene sheet material prepared in this embodiment has a gram weight of 42.3 g / m2 and a BET specific area of ​​15.8 m 2 / gm.

[0126] Example 10

[0127] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0128] The only difference is that in step (3),

[0129] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the sampled exhaust gas is 58 mg / m 3 ;

[0130] In the spinning solution, the mass fraction of the polymer is 15%.

[0131] The residence time of the solvent vapor in the adsorption tower is 15 seconds.

[0132] The temperature of the polyethylene glycol diethyl ether is 30°C.

[0133] The polyethylene sheet material prepared in this embodiment has a gram weight of 41.2 g / m2 and a BET specific area of ​​16.7 m 2 / gm.

[0134] Embodiment 11

[0135] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0136] The only difference is that in step (3),

[0137] (3) Tail gas adsorption: the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and the mass fraction of the solvent vapor in the tail gas is 6.132 g / m 3 The polyethylene glycol diethyl ether used to adsorb the solvent vapor is sprayed from the upper part of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower and the gas is discharged from the top of the adsorption tower. The mass fraction of the solvent vapor in the exhaust gas is 147 mg / m 3 ;

[0138] In the spinning solution, the mass fraction of the polymer is 15%.

[0139] The residence time of the solvent vapor in the adsorption tower is 15 seconds.

[0140] The temperature of the polyethylene glycol diethyl ether is 40°C.

[0141] The polyethylene sheet material prepared in this embodiment has a gram weight of 45.9 g / m2 and a BET specific area of ​​20.5 m 2 / gm.

[0142] From Example 3, as well as Examples 9, 10, and 11, it can be concluded that the lower the temperature, the better the adsorption effect. Too high a temperature is not conducive to adsorption. This is mainly because there is a temperature difference between the adsorbent and the solvent vapor. The greater the temperature difference, the higher the adsorption efficiency, that is, the more conducive to adsorption. Of course, the lower the temperature of the adsorbent, the higher the production cost, so it is better to select a temperature of 10 to 30°C for the adsorbent.

[0143] Example 12

[0144] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 1;

[0145] The only difference is that in step (3), polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0146] The polyethylene sheet material prepared in this embodiment has a gram weight of 47.9 g / m2 and a BET specific area of ​​17.5 m 2 / gm.

[0147] Embodiment 13

[0148] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those in Example 2;

[0149] The only difference is that in step (3), polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0150] The polyethylene sheet material prepared in this embodiment has a gram weight of 49.9 g / m2 and a BET specific area of ​​19.5 m 2 / gm.

[0151] Embodiment 14

[0152] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those in Example 3;

[0153] The only difference is that in step (3), polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0154] The polyethylene sheet material prepared in this embodiment has a gram weight of 49.9 g / m2 and a BET specific area of ​​20.1 m2 / gm.

[0155] Embodiment 15

[0156] A method for processing a polyethylene sheet material, wherein steps (1), (2), (4), (5), (6), and (7) are the same as those of Example 4;

[0157] The only difference is that in step (3), polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0158] The polyethylene sheet material prepared in this embodiment has a gram weight of 51.23 g / m2 and a BET specific area of ​​21.1 m 2 / gm.

[0159] Example 16

[0160] A method for processing a polyethylene sheet material, wherein steps (1), (2), (3), (4), (5), (6), and (7) are the same as those of Example 5;

[0161] The only difference is that in step (3), polyethylene glycol diethyl ether is replaced by polyethylene glycol methyl ethyl ether.

[0162] The polyethylene sheet material prepared in this embodiment has a gram weight of 52.23 g / m2 and a BET specific area of ​​21.5 m 2 / gm.

[0163] Embodiment 17

[0164] A method for processing a polyethylene sheet material, wherein steps (2), (3), (4), (5), (6), and (7) are the same as those of Example 1;

[0165] The only difference is that in step (1),

[0166] A method for processing a polyethylene sheet material comprises the following steps:

[0167] (1) preparing a spinning solution, adding a solvent into a reaction kettle, and then adding a polymer into the solvent to dissolve it to obtain a spinning solution;

[0168] The polymers are polyethylene particles and polypropylene, with a mass ratio of 9:1;

[0169] The solvent is 1,1-dichloro-2,2,2-trifluoroethane and 1,1,2,2,3,3,4,4-octafluorobutane; the volume ratio of the two is 7:3;

[0170] The polyethylene sheet material prepared in this embodiment has a gram weight of 53.4 g / m2 and a BET specific area of ​​22.6 m 2 / gm.

[0171] Embodiment 18

[0172] A method for processing a polyethylene sheet material, wherein steps (2), (3), (4), (5), (6), and (7) are the same as those of Example 1;

[0173] The only difference is that in step (1),

[0174] A method for processing a polyethylene sheet material comprises the following steps:

[0175] Prepare spinning solution, add solvent into a reaction kettle, then add polymer into the solvent and dissolve to obtain spinning solution;

[0176] The polymer is polyethylene particles, polybutene-1, and poly(4-methyl-1-pentene), with a mass ratio of 8:1:1;

[0177] The solvent is 1,1-dichloro-2,2,2-trifluoroethane and 1,1,2,2,3,3,4,4-octafluorobutane; the volume ratio of the two is 7:3;

[0178] The polyethylene sheet material prepared in this embodiment has a gram weight of 54.8 g / m2 and a BET specific area of ​​23.4 m 2 / gm.

[0179] Embodiment 19

[0180] A method for processing a polyethylene sheet material, wherein steps (2), (3), (4), (5), (6), and (7) are the same as those of Example 1;

[0181] The only difference is that in step (1),

[0182] A method for processing a polyethylene sheet material comprises the following steps:

[0183] Prepare spinning solution, add solvent into a reaction kettle, then add polymer into the solvent and dissolve to obtain spinning solution;

[0184] The polymer is polyethylene particles and polyvinylidene fluoride, and the mass ratio of the two is 8:2;

[0185] The solvent is 1,1-dichloro-2,2,2-trifluoroethane and 1,1,2,2,3,3,4,4-octafluorobutane; the volume ratio of the two is 7:3.

[0186] The polyethylene sheet material prepared in this embodiment has a gram weight of 55.9 g / m2 and a BET specific area of ​​25.9 m 2 / gm.

[0187] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a polyethylene sheet material, characterized in that: The following steps are involved: (1) preparing a spinning solution, adding a solvent into a reaction kettle, and then adding a polymer into the solvent to dissolve the polymer to obtain a spinning solution; (2) Spinning, using the spinning solution obtained in step 1 to spin by flash evaporation to obtain polyethylene flash fibers; and obtaining polyethylene sheet materials by hot pressing; (3) tail gas adsorption, the tail gas generated in step (2) is transported to the lower section of the adsorption tower by a fan, and polyethylene glycol diethyl ether for adsorbing solvent vapor is sprayed from the upper section of the adsorption tower and mixed with the solvent vapor in the adsorption tower. After the adsorption is completed, the liquid is discharged from the bottom of the adsorption tower, and the gas is discharged from the top of the adsorption tower; (4) The adsorbed liquid discharged from the bottom of the adsorption tower is transported to the heat exchanger through the first delivery pump for heat exchange and temperature increase; (5) The liquid after heat exchange is heated to 70-190°C by the first heater, transported to the upper section of the desorption tower, and sprayed into the desorption tower from the upper section of the desorption tower for desorption. The temperature in the desorption tower is 50-210°C and the pressure is below 5 KPa; (6) After desorption, the analyzed liquid is discharged from the bottom of the desorption tower and transported to the heat exchanger through the second delivery pump, where it undergoes heat exchange with the adsorbed liquid in the heat exchanger and is cooled to 0-40°C by the cooler before entering the adsorption tower. (7) The analyzed gas is discharged from the top of the analysis tower into the condenser, and the condensate obtained after condensation is stored in a recovery tank; The residence time of the solvent vapor in the adsorption tower is 5 to 25 seconds; The temperature of the polyethylene glycol diethyl ether is 15-25° C.; The solvent includes one or more of trichlorofluoromethane, 1,1-dichloro-2,2,2-trifluoroethane, 1,2-dichloro-1,2,2-trifluoroethane, 1,1-dichloro-2,2-difluoroethane, 1,2-dichloro-1,1-difluoroethane, 1,1-dichloro-1-fluoroethane, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,3,3-pentafluoropropane, 1,1,2,2,3,3,4,4-octafluorobutane, 1,1,1,3,3-pentafluorobutane, 2,3-dihydrodecafluoropentane, 1H,6H-perfluorohexane, 1H-perfluoroheptane, and 1H-perfluorohexane.

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