阅读说明：本技术 Pp/pe/pp三层共挤锂电池动力隔膜流延装置 (PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device ) 是由 李汪洋 胡伟 吴磊 张德顺 何祥燕 杨建军 张建安 陈曼 刘久逸 吴庆云 吴明元 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种三层共挤膜的流延装置,包括挤出头和设置于挤出头下方的流延机构,所述流延机构包括流延辊和与流延辊表面配合的压辊,所述压辊至少有两个,设置于流延辊的右上方,且两个压辊与流延辊之间设有间隙,用于压紧挤出头流延到流延辊上的三层共挤膜,其中位于下方的压辊与流延辊之间的距离小于位于上方的压辊与流延辊之间的距离,本发明克服了现有技术的不足,提高了三层共挤膜的力学性能,同时保证了流延辊的洁净,使该装置能够进行长期连续化生产。(The invention discloses a three-layer co-extrusion film casting device, which comprises an extrusion head and a casting mechanism arranged below the extrusion head, wherein the casting mechanism comprises casting rollers and press rollers matched with the surfaces of the casting rollers, at least two press rollers are arranged at the upper right of the casting rollers, a gap is arranged between each two press rollers and the corresponding casting roller and is used for pressing the extrusion head to cast the three-layer co-extrusion film on the casting rollers, and the distance between the lower press roller and the corresponding casting roller is smaller than the distance between the upper press roller and the corresponding casting roller.)

The utility model provides a PP PE PP three-layer is crowded lithium cell power diaphragm curtain coating device altogether, including extruding the head and setting up in extruding the curtain coating mechanism of head below, its characterized in that: the curtain coating mechanism includes the curtain coating roller and with curtain coating roller surface complex compression roller, the compression roller has two at least, sets up in the upper right side of curtain coating roller, and is equipped with the clearance between two compression rollers and the curtain coating roller for compress tightly and extrude the three-layer coextrusion membrane of head curtain coating to the curtain coating roller, wherein the distance between compression roller that is located the below and the curtain coating roller is less than the distance between the compression roller that is located the top and the curtain coating roller.

2. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 1, wherein: and the right side of the casting roller is also provided with a pair of transmission rollers for transmitting the three-layer co-extruded film.

3. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 1, wherein: the casting roller comprises a roller body and a roller shell, the roller body is a hollow steel roller, a plurality of through holes are formed in the surface of the steel roller, the roller shell is coated on the surface of the steel roller and is made of plastic with a microporous structure, cooling liquid steam with the temperature of 100-120 ℃ entering the steel roller is introduced into the right end of the steel roller, and the cooling liquid steam flows out of the left end of the steel roller.

4. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 3, wherein: the glass transition temperature of the plastic is greater than 120 ℃.

5. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 3, wherein: the plastic is polytetrafluoroethylene.

6. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 3, wherein: the pore diameter of the microporous structure of the roller shell is 1-30 um.

7. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 3, wherein: the inside exit of the left end of steel roller is equipped with the micropore screen panel, and steel roller is inside to be equipped with cooling liquid.

8. The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device of claim 3, wherein: the cooling liquid is water.

Technical Field

The invention relates to the technical field of casting devices, and particularly belongs to a PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device.

Background

In recent years, the lithium ion battery technology has been developed rapidly, and the performance of the lithium ion battery is determined by the separator as one of the core materials in the battery, so that the separator material and the preparation technology are urgently needed to be studied deeply. At present, the commercialized lithium battery separator is mainly a polyolefin-baked separator, and the preparation process is transiting from a dry method to a wet method, but separators of different material systems and different preparation processes have been developed in recent years.

The diaphragm is used as a key material of the lithium battery, plays a role in electronic isolation in the battery, prevents direct contact of a positive electrode and a negative electrode, allows lithium ions in electrolyte to freely pass through, and plays a vital role in guaranteeing safe operation of the battery. In special cases, such as accidents, punctures, battery abuse, etc., the separator is partially damaged to cause direct contact of the positive and negative electrodes, thereby causing severe battery reaction to cause ignition and explosion of the battery.

Therefore, in order to improve the safety of the lithium ion battery and ensure the safe and stable operation of the battery, the coating on-line considers that the diaphragm must meet the following conditions of (1) chemical stability: no reaction with electrolyte and electrode materials; (2) wettability: the electrolyte is easy to wet and does not extend or shrink; (3) high temperature resistance and high fusing isolation; (4) the mechanical strength is good, namely the tensile strength is good, so that the strength and the width are unchanged during automatic winding; (5) higher porosity to meet the ionic conductivity requirements.

Currently, commercially available lithium battery separators in the market are mainly microporous polyolefin separators mainly made of Polyethylene (PE) and polypropylene (PP), and such separators are widely used in lithium battery separators due to their advantages of low cost, good mechanical properties, excellent chemical stability and electrochemical stability. The practical application of the diaphragm also comprises a single-layer PP or PE diaphragm, a double-layer PE/PP composite diaphragm, a double-layer PP/PP composite diaphragm and a three-layer PP/PE/PP composite diaphragm. Wherein three-layer PP/PE/PP composite diaphragm is because mechanical properties and corrosion resistance are excellent, is widely used for battery diaphragm, and in current three-layer coextrusion casting device use, the surface unevenness of the three-layer coextrusion membrane that the curtain coating produced, the homogeneity is poor, and the bonding strength between the three-layer is not enough, and the curtain coating roller is dirty easily simultaneously, can't long-time continuous production.

Disclosure of Invention

The invention aims to provide a PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device, which overcomes the defects of the prior art.

In order to solve the problems, the technical scheme adopted by the invention is as follows:

PP/PE/PP three-layer is crowded lithium cell power diaphragm curtain coating device altogether, including extruding the head and setting up in the curtain coating mechanism of extruding the head below, curtain coating mechanism include the curtain coating roller and with curtain coating roller surface complex compression roller, the compression roller has two at least, sets up in the upper right side of curtain coating roller, and is equipped with the clearance between two compression rollers and the curtain coating roller for compress tightly and extrude the head curtain coating to the three-layer coextrusion membrane on the curtain coating roller, wherein the distance between compression roller that is located the below and the curtain coating roller is less than the distance between the compression roller that is located the top and the curtain coating roller.

Preferably, the right side of the casting roller is also provided with a pair of conveying rollers for conveying the three-layer co-extruded film.

Preferably, the casting roller comprises a roller body and a roller shell, the roller body is a hollow steel roller, a plurality of through holes are formed in the surface of the steel roller, the roller shell is coated on the surface of the steel roller, the roller shell is made of plastic with a microporous structure, cooling liquid steam with the temperature of 100-120 ℃ entering the steel roller is introduced into the right end of the steel roller, and the cooling liquid steam flows out from the left end of the steel roller.

Preferably, the glass transition temperature of the plastic is greater than 120 ℃.

Preferably, the plastic is polytetrafluoroethylene.

Preferably, the pore diameter of the microporous structure of the roll shell is 1-30 um.

Preferably, the inside exit of the left end of steel roller is equipped with the micropore screen panel, and steel roller is inside to be equipped with cooling liquid.

Preferably, the cooling liquid is water.

Preferably, the extrusion head includes the die head body, be equipped with the discharge gate on the right flank of die head body, the inside of die head body is to last and be equipped with first feed bin, second feed bin and third feed bin down, the right side of first feed bin, second feed bin and third feed bin is equipped with last ejection of compact portion, well ejection of compact portion and the ejection of compact portion down with the discharge gate intercommunication respectively, go up ejection of compact portion and down ejection of compact portion and set up respectively in the both sides of well ejection of compact portion, be equipped with first heating wire between first feed bin, second feed bin and the third feed bin and on the die head body of both sides, go up the even horizontal structure of upper and lower border of ejection of compact portion, well ejection of compact portion and lower ejection of compact portion, first feed bin and third feed bin have the inlet pipe through installing the branch union coupling in the die head body outside, the left side of second feed bin is equipped with the feed inlet.

Preferably, the die head base bodies on the upper side and the lower side of the discharge port are also internally provided with second heating wires, and the temperature of the first heating wire is 20-30 ℃ higher than that of the second heating wire.

Preferably, be equipped with arc portion between second feed bin and the well ejection of compact portion, the upper and lower surface of arc portion is the arc structure of symmetry setting.

Preferably, triangular edges are further arranged at the top ends of the die head bodies on the upper side and the lower side of the middle discharging part.

Preferably, the thickness of the die body between the upper discharging part, the middle discharging part and the lower discharging part at the triangular edge is 0.5-1.0 mm.

Preferably, the first bin and the second bin, and the second bin and the third bin are further connected through a constant pressure mechanism, and the constant pressure mechanism is used for keeping pressure balance between the first bin and the second bin, and between the second bin and the third bin.

Preferably, constant voltage mechanism includes the constant voltage pipe, the both ends of constant voltage pipe are equipped with and keep off the ring, keep off the intraductal movable mounting of constant voltage between the ring and have the piston, the both ends of constant voltage pipe are respectively through intercommunication portion and first feed bin, second feed bin or third feed bin intercommunication.

Compared with the prior art, the invention has the following implementation effects:

according to the casting device, the two press rolls with different distances from the casting roll are arranged, so that the three-layer co-extrusion film cast on the casting roll by the extrusion head is further cooled and extruded, the bonding strength inside the three-layer co-extrusion film is enhanced, and the mechanical property of the three-layer co-extrusion film is improved.

The casting roller adopts the structure of the roller shell and the steel roller, so that cooling liquid steam introduced into the steel roller can enter the roller shell from the through hole and flows to the surface of the casting roller from the microporous structure of the roller shell, on one hand, the temperature of the casting roller is kept, and the three-layer co-extrusion film can be cooled by the casting roller, on the other hand, the cooling liquid steam flowing out of the microporous structure can effectively prevent the three-layer co-extrusion film from being adhered to the surface of the casting roller, so that the cooled three-layer co-extrusion film can be favorably peeled off, the cleanness of the casting roller is ensured, and the device can be used for long-term continuous production.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is an enlarged view taken at D in FIG. 1;

FIG. 3 is a cross-sectional view of a casting roll;

FIG. 4 is a front view of the extrusion head;

FIG. 5 is a top view of the extrusion head;

FIG. 6 is a cross-sectional view A-A of FIG. 5;

FIG. 7 is a cross-sectional view taken along line B-B of FIG. 5;

fig. 8 is an enlarged view at C in fig. 7.

Description of reference numerals: 1. a die head body; 11. a feed inlet; 12. a discharge port; 13. a feed pipe; 14. a branch pipe; 15. a first storage bin; 16. a second storage bin; 161. a lower discharge part; 17. a third storage bin; 171. an arc-shaped portion; 172. a middle discharge part; 18. a first heating wire; 19. a second heating wire; 20. triangular edges; 101. a constant pressure tube; 102. a baffle ring; 103. a piston; 104. a communicating portion; 2. a casting roll; 21. a steel roll; 22. a through hole; 23. a roll shell; 3. a compression roller; 4. a transfer roller; 5. a mesh enclosure; 6. cooling liquid; 7. three layers of co-extruded films.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation to be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1

The PP/PE/PP three-layer co-extrusion lithium battery power diaphragm casting device comprises an extrusion head and a casting mechanism arranged below the extrusion head, wherein the casting mechanism comprises a casting roller 2 and a pressing roller 3 matched with the surface of the casting roller 2, at least two pressing rollers 3 are arranged, the upper right side of the casting roller 2 is arranged, a gap is formed between the two pressing rollers 3 and the casting roller 2, the three-layer co-extrusion film 7 cast onto the casting roller 2 by the extrusion head is compressed, the distance between the pressing roller 3 and the casting roller 2 below is smaller than the distance between the pressing roller 3 and the casting roller 2 above, and a pair of transmission rollers 4 used for transmitting the three-layer co-extrusion film 7 are further arranged on the right side of the casting roller 2.

The casting device is through setting up two compression rollers 3 different with casting roller 2 apart from, makes the head curtain coating of extruding obtain further cooling extrusion to the three-layer coextrusion membrane 7 on casting roller 2, has strengthened the inside joint strength of three-layer coextrusion membrane 7, has improved the mechanical properties of three-layer coextrusion membrane 7.

The casting roller 2 comprises a roller body and a roller shell 23, the roller body is a hollow steel roller 21, the surface of the steel roller 21 is provided with a plurality of through holes 22, the roller shell 23 is coated on the surface of the steel roller 21, the roller shell 23 is made of plastic with a microporous structure, the plastic is polytetrafluoroethylene, the glass transition temperature is higher than 120 ℃, the pore diameter of the microporous structure of the roller shell 23 is 20 microns, the pore diameter of the microporous structure can be selected within the range of 1-30 microns according to the requirements of a produced three-layer co-extrusion film, cooling liquid 6 steam with the temperature of 100 ℃ entering the steel roller 21 is introduced into the right end of the steel roller 21, the cooling liquid 6 steam flows out from the left end of the steel roller 21, a microporous mesh enclosure 5 is arranged at an outlet in the left end of the steel roller 21, the cooling liquid 6 is arranged in the steel roller 21, the cooling liquid 6 is water, and other liquids with the temperature of 100 ℃ and 120 ℃ can also be used; the screen 5 can prevent the cooling liquid 6 from flowing out from the left end outlet of the steel roll 21 in a large amount when the casting roll 2 rotates, and the screen 5 can allow the steam to pass through. And casting roll 2 adopts the structure of roll shell 23 and steel roll 21, make the inside cooling liquid 6 steam that lets in of steel roll 21 can get into roll shell 23 from through-hole 22, and flow to the surface of casting roll 2 from the microporous structure of roll shell 23, make the temperature of casting roll 2 obtain keeping on the one hand, make casting roll 2 can cool down three-layer coextrusion membrane 7, on the other hand, the cooling liquid 6 steam that the microporous structure flows out can effectually avoid three-layer coextrusion membrane 7 to adhere on the surface of casting roll 2, be favorable to the peeling off of three-layer coextrusion membrane 7 after the cooling, the cleanness of casting roll 2 has been guaranteed simultaneously, make the device can carry out serialization production.

Example 2

As a further technical solution of the present invention, the extrusion head shown in fig. 4-7 includes a die head body 1, a discharge port 12 is disposed on a right side surface of the die head body 1, a first bin 15, a second bin 16 and a third bin 17 are disposed inside the die head body 1 from top to bottom, an upper discharge portion, a middle discharge portion 172 and a lower discharge portion 161 which are communicated with the discharge port 12 are respectively disposed on right sides of the first bin 15, the second bin 16 and the third bin 17, the upper discharge portion and the lower discharge portion 161 are respectively disposed on two sides of the middle discharge portion 172, the first bin 15, the second bin 16 and the third bin 17 buffer the molten material entering the die head, so as to avoid direct extrusion compounding of the conventional basic process, and the molten material passes through the buffer of the first bin 15, the second bin 16 and the third bin 17, so that the molten material in the first bin 15, the second bin 16 and the third bin 17 can be uniformly extruded from the upper discharge portion, the lower discharge portion and the third bin 17, Well discharge portion 172 and lower discharge portion 161 flow out, and go up discharge portion, well discharge portion 172 and the pressure of ejection of compact down even, avoided the problem that each layer thickness of three-layer composite that direct extrusion in-process pressure variation leads to changes greatly.

First heating wires 18 are arranged among the first bin 15, the second bin 16 and the third bin 17 and on the die head bodies 1 on two sides, second heating wires 19 are arranged in die head base bodies on the upper side and the lower side of the discharge port 12, the temperature of the first heating wires 18 is 30 ℃ higher than that of the second heating wires 19, specific temperatures can be selected within the range of 20-30 ℃ as required, the first bin 15 and the third bin 17 are connected with a feed pipe 13 through branch pipes 14 arranged on the outer side of the die head body 1, and a feed port 11 is arranged on the left side of the second bin 16. The first heating wire 18 can prevent the molten material in the die head body 1 from being solidified, and the second heating wire 19 has a higher temperature than the first heating wire 18, so as to further raise the temperature of each extruded layer, so that each layer is expanded in the discharge port 12, and the composite strength between each extruded layer is improved.

The upper and lower edges of the upper discharging part, the middle discharging part 172 and the lower discharging part 161 are uniformly in a horizontal structure, so that the surface of the extruded layer flowing out of each discharging part is smooth and flat. Be equipped with arc portion 171 between second feed bin 16 and well discharge portion 172, the upper and lower surface of arc portion 171 is the arc structure that the symmetry set up, and the arc structure extrudes the melting material that second feed bin 16 flowed out, and the structure on the layer is extruded in the middle of making the outflow of well discharge portion 172 is even. The top ends of the die head bodies 1 on the upper side and the lower side of the middle discharging part 172 are also provided with triangular ribs 20, the thickness of the die head bodies 1 among the upper discharging part, the middle discharging part 172 and the lower discharging part 161 at the triangular ribs 20 is 0.6mm, the specific thickness can be selected within the range of 0.5-1.0mm according to needs, and the triangular ribs 20 play a guiding role to avoid pores among extrusion layers.

Example 3

As a further technical solution of the present invention, as shown in fig. 7-8, the first silo 15 and the second silo 16, and the second silo 16 and the third silo 17 are further connected by a constant pressure mechanism, and the constant pressure mechanism is used for maintaining pressure balance between the first silo 15 and the second silo 16, and between the second silo 16 and the third silo 17. The constant pressure mechanism includes constant pressure pipe 101, and the both ends of constant pressure pipe 101 are equipped with and keep off ring 102, and movable mounting has piston 103 in the constant pressure pipe 101 between keeping off ring 102, and the both ends of constant pressure pipe 101 are respectively through intercommunication portion 104 and first feed bin 15, second feed bin 16 or third feed bin 17 intercommunication. The constant pressure mechanism enables the pressure of the first storage bin 15, the second storage bin 16 and the third storage bin 17 to be equal in the extrusion process, and avoids sudden change of feeding pressure, so that the problem that the thickness of the extruded layer is thinned due to extrusion of the extruded layer with large pressure to the extruded layer with small pressure in each layer extruded from the upper discharging part, the middle discharging part 172 and the lower discharging part 161 is solved.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.