阅读说明：本技术 一种锂电池隔膜铸片的成型装置及其成型方法 (Forming device and forming method for lithium battery diaphragm casting sheet ) 是由 袁海朝 李董超 徐锋 韩义龙 杜鹏宇 于 2019-08-02 设计创作，主要内容包括：本发明公开了锂电池隔膜铸片的成型装置及成型方法,包括挤出机、挤出模头、多组铸轧冷却辊组和冷却定型辊；挤出机用于挤出熔融的聚乙烯；挤出模头与挤出机的出口连接,用于承接挤出机挤出的熔融的聚乙烯通过挤出模头挤出聚乙烯熔体；铸轧冷却辊组承接在挤出模头的出口处,用于将挤出的聚乙烯熔体流延并牵引至铸轧冷却辊组上以形成流延膜；冷却定型辊承接在铸轧冷却辊组的下料处,用于将形成的流延膜流延并牵引至冷却定型辊上,以冷却结晶成型形成铸片。铸轧冷却辊组对聚乙烯熔体流延的两面进行初步冷却,保证两面的冷却效果一致,再通过冷却定型辊定型形成铸片,减少铸片内部的成孔剂从背辊侧渗出,使得微孔隔膜的均匀一致,提高产品质量。(the invention discloses a forming device and a forming method of a lithium battery diaphragm cast sheet, which comprises an extruder, an extrusion die head, a plurality of groups of cast-rolling cooling roller sets and cooling shaping rollers, wherein the plurality of groups of cast-rolling cooling roller sets are arranged on the extruder; an extruder for extruding molten polyethylene; the extrusion die head is connected with an outlet of the extruder and is used for receiving the molten polyethylene extruded by the extruder and extruding polyethylene melt through the extrusion die head; the casting and rolling cooling roller group is connected with an outlet of the extrusion die head and used for casting and drawing the extruded polyethylene melt onto the casting and rolling cooling roller group to form a casting film; the cooling shaping roller is connected with the discharging position of the casting and rolling cooling roller group and used for casting and drawing the formed casting film to the cooling shaping roller so as to form a casting sheet through cooling crystallization. The cast rolling cooling roll group carries out primary cooling to the two sides of polyethylene melt curtain coating, guarantees that the cooling effect on two sides is unanimous, and rethread cooling sizing roller is stereotyped and is formed the casting piece, reduces the inside pore-forming agent of casting piece and oozes out from the back roll side for microporous diaphragm's even unanimity improves product quality.)

1. The utility model provides a forming device of lithium battery diaphragm casting sheet which characterized in that: comprises an extruder, an extrusion die head, a plurality of groups of casting-rolling cooling roller sets and cooling shaping rollers;

The extruder is used for extruding molten polyethylene;

The extrusion die head is connected with an outlet of the extruder and is used for receiving the molten polyethylene extruded by the extruder and extruding polyethylene melt through the die head;

the casting and rolling cooling roller group is arranged between the extrusion die head and the cooling shaping roller, is positioned below an outlet of the extrusion die head and is used for drawing extruded polyethylene melt onto the casting and rolling cooling roller group so as to form a semi-solid casting film through cooling;

The cooling shaping roller is connected with the blanking part of the casting and rolling cooling roller group and used for drawing the formed casting film to the cooling shaping roller so as to be cooled, crystallized and formed to form a solid casting sheet.

2. The molding apparatus as defined in claim 1, wherein: and the multiple groups of casting-rolling cooling roller groups are arranged between the extrusion die head and the cooling shaping roller in an arc shape, and the center of the arc is the intersection point of the vertical axis of the cooling shaping roller and the horizontal line at the die lip of the extrusion die head.

3. The molding apparatus as defined in claim 2, wherein: the number of the casting and rolling cooling roller groups is 2-8.

4. The molding apparatus as defined in claim 3, wherein: each casting and rolling cooling roller of the casting and rolling cooling roller group is a hollow roller core, and a rotary joint of the casting and rolling cooling roller is communicated with a temperature controller which is externally used for circulating cooling water, so that the temperature of the casting and rolling cooling roller is ensured to be constant.

5. The molding apparatus as defined in claim 4, wherein: the die head width of the length extruder of the cast-rolling cooling roller is adaptive.

6. A method for molding a lithium battery separator cast piece based on the molding device of claim 5, comprising the steps of:

(1) Extruding: adding a polyethylene raw material into an extruder, and extruding a polyethylene melt through an extrusion die head of the extruder;

(2) pre-cooling: the polyethylene melt is cast to the surface of the casting-rolling cooling roller group from the extrusion die head, and the two sides of the polyethylene melt are uniformly cooled to form a semi-solid cast film;

(3) Cooling and shaping: and (3) casting the casting film formed in the step (2) to a cooling sizing roller, and cooling, crystallizing and forming on the cooling sizing roller to obtain a casting sheet.

7. The molding method according to claim 6, wherein: and (4) after the cast sheet obtained in the step (3), carrying out heat treatment annealing on the cast sheet, then carrying out bidirectional synchronous drawing pore-forming, drying and shaping to obtain the lithium battery diaphragm.

8. The molding method according to claim 7, wherein: in the step (4), when the cast sheet is stretched synchronously in two directions, the stretching ratio is 1-5 times in the transverse direction and 5-10 times in the longitudinal direction.

9. The molding method according to claim 8, wherein: the melting temperature of the molten polyethylene is 140 ℃ to 280 ℃.

10. The molding method according to claim 9, wherein: the temperature of the cast-rolling cooling roller is 30-120 ℃.

Technical Field

the invention belongs to the field of electrochemistry, and particularly relates to a forming device and a forming method for a lithium battery diaphragm casting sheet.

Background

The lithium battery diaphragm is a polyethylene microporous film, and the preparation process thereof is generally divided into a dry method and a wet method, wherein the two preparation methods both need to melt pretreated raw materials in an extrusion system and extrude melt from a die head, and the melt forms a base film casting sheet with a specific crystal structure after casting and cooling.

in the stage of diaphragm production, in which a base film casting sheet is formed by casting, a casting melt is suspended for a certain distance and then contacted with a cooling setting roller, the casting is attached and wound on the cooling setting roller for cooling and setting, so that a solid thick sheet is formed, a pore-forming agent and polyethylene are separated by thermotropic property, and after the surface of the casting sheet is rapidly cooled, the pore-forming agent is contained in the base film casting sheet of the thick sheet. Because there is one section distance between curtain coating and the cooling design roller to when the attached winding of curtain coating was on the cooling design roller, only had the roll surface contact of one side and cooling design roller, thereby caused the opposite side of curtain coating to be in the natural cooling state, lead to the cooling effect inconsistent on curtain coating two sides, the microporous construction of direct influence diaphragm, and then the air permeability who influences the diaphragm.

At present, in the prior art, in order to further improve the performance of the lithium battery diaphragm, a coating process is generally required on the surface of the diaphragm, and the difference of ventilation and increment of two surfaces of the coated diaphragm is large due to the inconsistency of the microporous structures when the base film casting sheet is cooled and shaped, so that the yield of products is influenced.

disclosure of Invention

the invention aims to provide a forming device for a lithium battery diaphragm cast sheet, which has the advantages of simple structure, simple operation, cooling of two sides of a base film cast sheet, improvement of the air permeability of a diaphragm and high product percent of pass.

The technical scheme of the invention is as follows:

the utility model provides a forming device of lithium battery diaphragm casting sheet which characterized in that: comprises an extruder, an extrusion die head, a plurality of groups of casting-rolling cooling roller sets and cooling shaping rollers;

The extruder is used for extruding molten polyethylene;

The extrusion die head is connected with an outlet of the extruder and is used for receiving the molten polyethylene extruded by the extruder and extruding polyethylene melt through the die head;

the casting and rolling cooling roller group is arranged between the extrusion die head and the cooling shaping roller, is positioned below an outlet of the extrusion die head and is used for drawing extruded polyethylene melt onto the casting and rolling cooling roller group so as to form a semi-solid casting film through cooling;

The cooling shaping roller is connected with the blanking part of the casting and rolling cooling roller group and used for drawing the formed casting film to the cooling shaping roller so as to be cooled, crystallized and formed to form a solid casting sheet.

In the technical scheme, the multiple groups of casting-rolling cooling roller groups are arranged between the extrusion die head and the cooling shaping roller in an arc shape, the center of the arc is the intersection point of the vertical axis of the cooling shaping roller and the horizontal line at the die lip of the extrusion die head, and the radius of the arc is 250-1000 mm.

In the technical scheme, the number of the casting and rolling cooling roller groups is 2-8.

In the technical scheme, each casting and rolling cooling roller of the casting and rolling cooling roller group is a hollow roller core, and a rotary joint of the casting and rolling cooling roller is communicated with an external temperature controller for circulating cooling water so as to ensure that the temperature of the casting and rolling cooling roller is constant.

In the technical scheme, the length of the casting and rolling cooling roller is adaptive to the die head width of the extruder, the length of the casting and rolling cooling roller is more than or equal to +100 mm of the die head width of the extruder, the roller is arranged in the center, the allowance left on each side is more than or equal to 50mm, and the diameter of the casting and rolling cooling roller is 100-300 mm.

The invention also aims to provide a forming method of the lithium battery diaphragm cast sheet based on the forming device, which comprises the following steps:

(1) Extruding: adding a polyethylene raw material into an extruder, and extruding a polyethylene melt through an extrusion die head of the extruder;

(2) Pre-cooling: the polyethylene melt is cast to the surface of the casting-rolling cooling roller group from the extrusion die head, and the two sides of the polyethylene melt are uniformly cooled to form a semi-solid cast film;

(3) Cooling and shaping: and (3) casting the casting film formed in the step (2) to a cooling sizing roller, and cooling, crystallizing and forming on the cooling sizing roller to obtain a solid casting sheet.

according to the technical scheme, after the cast sheet obtained in the step (3), the cast sheet is subjected to heat treatment annealing, and then bidirectional synchronous stretching hole forming, drying and shaping are carried out, so that the lithium battery diaphragm is obtained.

in the above technical solution, in the step (4), when the cast sheet is stretched synchronously in both directions, the stretching ratio is 1 to 5 times in the transverse direction and 5 to 10 times in the longitudinal direction.

in the above technical scheme, the melting temperature of the molten polyethylene is 140 ℃ to 280 ℃.

In the technical scheme, the temperature of the cast-rolling cooling roller is 30-120 ℃.

The invention has the advantages and positive effects that:

1. cast the two sides of rolling cooling roll group polyethylene melt curtain coating and carry out the primary cooling to guarantee that the cooling effect on two sides is unanimous, later the shaping roller of rethread cooling is stereotyped and is formed the casting piece, effectively reduces the inside pore-forming agent of casting piece and oozes out from the back roll side, makes the even unanimity of micropore diaphragm, improves product quality in the subsequent order.

2. the multiple groups of casting-rolling cooling roller groups arranged between the lip of the extrusion die head and the cooling shaping rollers apply pressure on the surface layers of two surfaces of the casting, and the pressure is rapidly cooled in advance to form a solid state, so that the cooling shaping effect of the two surfaces of the casting is greatly improved.

Drawings

FIG. 1 is a schematic view of the structure of a molding apparatus of the present invention;

Fig. 2 is a sectional view of the cast cooling roll of the present invention.

In the figure:

1. Extruder 2, extrusion die 3, cast-rolling cooling roller set

4. Cooling shaping roller 5, roller core 6 and rotary joint

7. Roller sleeve 8 and water inlet

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of the invention in any way.