WO2023096206A1 - Method for preparing urethane-based prepolymer - Google Patents

Abstract

Provided is a method for preparing a urethane-based prepolymer, the method comprising the steps of: introducing and dissolving a diisocyanate-based compound in a reaction bath; introducing a mixture, in which a sodium salt is dispersed in polyol, into the reaction bath, in which the diisocyanate-based compound is dissolved, to carry out a primary reaction; introducing a chain extender, a cross-linking agent, and a catalyst after the primary reaction to carry out a secondary reaction; and introducing a solvent after the secondary reaction.

Description

Manufacturing method of urethane-based prepolymer

It relates to a method for producing a urethane-based prepolymer.

In order to manufacture a lithium ion battery, it is basically necessary to attach an active material to a current collector. A binder is used in an electrode for a lithium secondary battery and serves to mechanically stabilize the electrode. In addition, the binder prevents the coupling between the active material or the conductive material from loosening when charging and discharging are repeatedly performed. A slurry is made by mixing a negative electrode active material, a conductive material, a solvent, and a binder and attached to the electrode. If the binder is not added when making the slurry, it is not evenly distributed on the current collector.

These binders are classified into solvent-based binders and water-based binders. Recently, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC), which are water-based binders, are mainly used instead of polyvinylidene fluoride (PVDF), which is a solvent-based binder. Energy density can be increased by increasing the content of the active material and reducing the content of the binder, but polyvinylidene fluoride (PVDF) has limitations in reducing the binder content. On the other hand, water-based binders such as styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) can bind each other flexibly and firmly with minimal adhesion, and bind more tightly than polyvinylidene fluoride (PVDF). characteristics are excellent.

In this regard, it is required to develop a prepolymer type binder as a solvent-based binder having excellent adhesive strength and heat resistance compared to a water-based binder and a solvent-based binder, polyvinylidene fluoride (PVDF).

In addition, the lithium secondary battery can easily generate heat by continuously exchanging electricity, and at this time, the separator is very vulnerable to heat. For example, in the case of a polyethylene (PE) separator, it melts at around 130° C., causing pores to melt, and completely melts at 150° C. or higher. To prevent this, ceramic particles or the like are coated with a polymer or a fluorine-based separator is used as a separator. Therefore, it is very important to increase the heat resistance of the separation membrane and to prevent the melting of pores so that it has stability. In consideration of this, development of a material for coating the separator is also required.

In addition, in sodium solid-state batteries, which are attracting attention as next-generation batteries to replace lithium ion batteries, development of materials for interlayers that enhance thermal and mechanical stability of solid electrolytes is also required.

One embodiment provides a method for producing a multi-purpose urethane-based prepolymer that is excellent in heat resistance, adhesion, flowability, permeability and ion conductivity and can be applied to binders and separator coating agents for lithium secondary batteries and interlayers for sodium solid-state batteries.

One embodiment comprises the steps of dissolving by introducing a diisocyanate-based compound into a reaction vessel; Injecting a mixture in which sodium salt is dispersed in polyol into a reaction vessel in which the diisocyanate-based compound is dissolved, and subjecting the mixture to a primary reaction; Injecting a chain extender, a crosslinking agent and a catalyst after the first reaction to perform a second reaction; And it provides a method for producing a urethane-based prepolymer comprising the step of introducing a solvent after the secondary reaction.

The diisocyanate-based compound may include methylene diphenyl diisocyanate, hexamethylene diisocyanate, or a combination thereof.

The polyol may include polyethylene glycol, polypropylene glycol, or a combination thereof.

The polyol may be the polyethylene glycol, and the polyethylene glycol may have a weight average molecular weight of 400 g/mol to 1,000 g/mol.

The polyol may be the polypropylene glycol, and the polypropylene glycol may have a weight average molecular weight of 1,000 g/mol to 5,000 g/mol.

The sodium salt is sulfanilic acid sodium salt, 4-aminobenzoic acid sodium salt, 2-aminobenzene-1,4-disulfonic acid sodium salt, 2-aminobenzene-1,4-dica carboxylic acid sodium salts, hydrates thereof, or combinations thereof.

The urethane-based prepolymer may include 3.0 wt% to 3.4 wt% of NCO groups.

The viscosity of the urethane-based prepolymer may be 1000 cps to 1500 cps.

The specific gravity of the urethane-based prepolymer may be 0.97 to 0.98.

The heat resistance of the urethane-based prepolymer may be 180°C to 220°C.

The adhesive strength of the urethane-based prepolymer may be 1.1 kgf/cm ² to 1.5 kgf/cm ² with respect to the shear of the polyethylene film or the polypropylene film.

The urethane-based prepolymer may be used for a binder for a lithium secondary battery, a separator coating agent for a lithium secondary battery, an interlayer for a sodium solid-state battery, or a combination thereof.

The urethane-based prepolymer prepared according to one embodiment has excellent heat resistance, adhesiveness, flowability, permeability, and ion conductivity, and thus can be applied to both binders and separator coating agents for lithium secondary batteries and interlayers for sodium solid-state batteries.

1 is a structural diagram of a urethane-based prepolymer prepared according to one embodiment.

Hereinafter, embodiments will be described in detail so that those skilled in the art can easily implement them. However, implementations may take many different forms and are not limited to the implementations described herein.

Dissolving the urethane-based prepolymer according to an embodiment by introducing a diisocyanate-based compound into a reaction vessel; Injecting a mixture in which sodium salt is dispersed in polyol into a reaction vessel in which the diisocyanate-based compound is dissolved, and subjecting the mixture to a primary reaction; Injecting a chain extender, a crosslinking agent and a catalyst after the first reaction to perform a second reaction; And it may be prepared by including the step of introducing a solvent after the secondary reaction.

The urethane-based prepolymer prepared by the above method has excellent properties in heat resistance, adhesiveness, flowability, permeability and ionic conductivity. Accordingly, it can be applied to both the binder and separator coating agent for lithium secondary batteries and the interlayer for sodium solid-state batteries.

Specifically, first, the temperature of the reaction vessel is raised to 50° C. to 60° C., and then the diisocyanate-based compound is completely dissolved.

The diisocyanate-based compound may include methylene diphenyl diisocyanate, hexamethylene diisocyanate, or a combination thereof.

The diisocyanate-based compound may be used in an amount of 15 wt % to 40 wt %, for example, 25 wt % to 32 wt %, based on the total amount of the urethane-based prepolymer. When the diisocyanate-based compound is added within the above content range, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

Additives including an antioxidant, a thermal stabilizer, or a combination thereof may be additionally added to the reactor. The additive may be added in an amount of 0.1% to 10% by weight based on the total amount of the urethane-based prepolymer. In addition, the additive may be dispersed by stirring at a speed of 1000 rpm to 1200 rpm, and then introduced into the reaction vessel.

Subsequently, a first reaction is performed by slowly introducing a mixture in which a sodium salt is dispersed in a polyol. At this time, the mixture may be introduced into the reactor in a vacuum state.

The mixture in which the diisocyanate-based compound and the sodium salt are dispersed in the polyol may be added at a weight ratio of 50:50 to 30:70 and reacted, for example, at a weight ratio of 50:50 to 40:60. there is. When added within the above content ratio range, it is possible to prepare a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity.

The mixture in which the sodium salt is dispersed in the polyol may be a mixture in which 1 wt% to 20 wt% of the sodium salt is dispersed in 80 wt% to 99 wt% of the polyol, for example, 90 wt% to 99 wt% of the polyol. 1% to 10% by weight of the sodium salt may be dispersed therein. When the polyol and the sodium salt are mixed within the above content ratio range, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ion conductivity can be prepared.

The mixture in which the sodium salt is dispersed in the polyol is stirred at a rate of 1400 rpm to 1700 rpm, for example, 1500 rpm to 1600 rpm for 10 minutes to 40 minutes, for example, 20 minutes to 1600 rpm, until completely dissolved. It can be obtained by dispersing by stirring for 30 minutes. When the mixture obtained within the above conditions is used in preparing the urethane-based prepolymer, a prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

As the polyol, a polyol having two or three OH groups may be used. Specifically, the polyol may include polyethylene glycol, polypropylene glycol, or a combination thereof.

Among examples of the polyol, polyethylene glycol may be used. The polyethylene glycol may have a weight average molecular weight of 400 g/mol to 1,000 g/mol, for example, 400 g/mol to 900 g/mol. In addition, the polyethylene glycol may have a viscosity of 100 cps to 300 cps, for example, 150 cps to 250 cps. When polyethylene glycol having a weight average molecular weight within the above range is used, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

In addition, polypropylene glycol may be used among examples of the polyol. The polypropylene glycol may have a weight average molecular weight of 1,000 g/mol to 5,000 g/mol, for example, 1,000 g/mol to 2,000 g/mol. In addition, the polypropylene glycol may have a viscosity of 100 cps to 300 cps, for example, 150 cps to 250 cps. When polypropylene glycol having a weight average molecular weight within the above range is used, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The sodium salt is sulfanilic acid sodium salt, 4-aminobenzoic acid sodium salt, 2-aminobenzene-1,4-disulfonic acid sodium salt, 2-aminobenzene-1,4-dica carboxylic acid sodium salts, hydrates thereof, or combinations thereof. For example, the sodium salt may include a sodium salt of sulfanilic acid, a sodium salt of 4-aminobenzoic acid, a hydrate thereof, or a combination thereof.

The first reaction is carried out by raising the temperature of the reaction tank to 70 ° C to 100 ° C, for example, 80 ° C to 90 ° C, and at a speed of 100 rpm to 150 rpm, for example, 110 rpm to 150 rpm for 30 minutes to 2 It may be performed for a period of time, for example, 1 hour to 2 hours. Urethane-based prepolymer with excellent heat resistance, adhesiveness, flowability, permeability and ion conductivity when the primary reaction, that is, the reaction of the mixture in which the diisocyanate-based compound and the sodium salt are dispersed in the polyol in the reaction tank is performed within the above range of conditions can be obtained.

Subsequently, a secondary reaction is performed by introducing a chain extender, a crosslinking agent and a catalyst. Specifically, a catalyst may be introduced after sequentially introducing a chain extender and a crosslinking agent for adhesion enhancement and crosslinking reaction.

The chain extender may use 1,3-butylene glycol (1,3-BD), but is not limited thereto.

The chain extender may be added in an amount of 0.1 wt% to 5 wt%, for example, 0.5 wt% to 2 wt%, based on the total amount of the urethane-based prepolymer.

The crosslinking agent may use trimethylolpropane (TMP), but is not limited thereto.

The crosslinking agent may be added in an amount of 0.1 wt% to 5 wt%, for example, 0.5 wt% to 2 wt%, based on the total amount of the urethane-based prepolymer. When the crosslinking agent is added within the above content range, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

As the catalyst, di-N-butylbis(dodecylthio)tin may be used, but is not limited thereto.

The catalyst may be added in an amount of 0.01 wt% to 1 wt%, for example, 0.01 wt% to 0.1 wt%, based on the total amount of the urethane-based prepolymer.

The secondary reaction may be performed for 10 minutes to 1 hour, for example, 20 minutes to 50 minutes.

Then, after the second reaction, the reaction tank temperature may be reduced to 50° C. to 80° C., and half of the solvent of the predetermined amount may be first added, followed by stirring for 10 minutes to 30 minutes. Thereafter, the second half of the solvent may be added and stirred again for 10 to 30 minutes. When performed within the above conditions, a urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The solvent may be toluene or the like, but is not limited thereto.

Subsequently, after the reaction is completely completed, additives such as antioxidants and curing catalysts may be additionally added while maintaining the temperature at 50° C. to 80° C.

The urethane-based prepolymer prepared according to one embodiment may include 3.0 wt% to 3.4 wt% of NCO groups, for example, 3.1 wt% to 3.3 wt%. When the urethane-based prepolymer includes the NCO group within the above content range, the urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The viscosity of the urethane-based prepolymer may be 1000 cps to 1500 cps, for example, 1000 cps to 1300 cps. When the viscosity of the urethane-based prepolymer is within the above range, the urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The specific gravity of the urethane-based prepolymer may be 0.97 to 0.98. When the specific gravity of the urethane-based prepolymer is within the above range, the urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The heat resistance of the urethane-based prepolymer may be 180 °C to 220 °C, for example, 185 °C to 215 °C. When the heat resistance of the urethane-based prepolymer is within the above range, the urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The adhesive strength of the urethane-based prepolymer may be 1.1 kgf/cm ² to 1.5 kgf/cm ² , for example, 1.1 kgf/cm ² to 1.3 kgf/cm ² with respect to the shear of the polyethylene film or the polypropylene film. . When the adhesive strength of the urethane-based prepolymer is within the above range, the urethane-based prepolymer having excellent heat resistance, adhesiveness, flowability, permeability and ionic conductivity can be obtained.

The structure of the urethane-based prepolymer prepared as described above may refer to FIG. 1. 1 is a structural diagram of a urethane-based prepolymer according to one embodiment. Referring to FIG. 1, the left structure shows a mixture in which sodium salt is dispersed in a polyol, and is a structural diagram before crosslinking with a diisocyanate-based compound occurs in the first reaction. When a mixture in which sodium salt is dispersed in a polyol having such a structure is put into a reaction vessel in which a diisocyanate-based compound is dissolved and mixed, crosslinking may occur to form a rigid structure connected to each other as shown in the right structure.

The urethane-based prepolymer having the above structure not only has high stiffness and high heat resistance due to crosslinking, but also has excellent adhesion, flowability, permeability and ion conductivity. Accordingly, when used as a binder for a lithium secondary battery, it is easy to mix and disperse with an active material, and when used as an interlayer for a sodium solid-state battery, it is sufficient to cope with the thermal and mechanical stability of the solid electrolyte. Therefore, the urethane-based prepolymer according to one embodiment may be usefully used for a binder for a lithium secondary battery, a separator coating agent for a lithium secondary battery, an interlayer for a sodium solid-state battery, or a combination thereof.

Hereinafter, specific embodiments of the present invention are presented. However, the embodiments described below are only intended to specifically illustrate or explain the present invention, and the present invention should not be limited thereto. In addition, since the content not described herein can be sufficiently technically inferred by those skilled in the art, the description thereof will be omitted.

(Manufacture of urethane-based prepolymer)

Example 1

After raising the temperature of the reactor to 60° C., 25 wt% of methylene diphenyl diisocyanate (BASF's M, NCO content of 33 wt% and specific gravity of 1.25 based on the total amount of methylene diphenyl diisocyanate) was added and completely dissolved.

Subsequently, 0.8% by weight of a heat stabilizer (FA-06, ZIKO) was dispersed by high-speed stirring at a speed of 1100 rpm, and then introduced into the reaction vessel.

Subsequently, a mixture obtained by dispersing 5% by weight of 4-aminobenzoic acid sodium salt in 95% by weight of polypropylene glycol (BASF) having a weight average molecular weight of 1,000 g/mol was prepared. At this time, it was dispersed by stirring at high speed for 30 minutes at a speed of 1500 rpm until completely dissolved.

42.3% by weight of the obtained mixture, that is, a mixture in which 4-aminobenzoic acid sodium salt was dispersed in polypropylene glycol, was gradually added after the reactor was evacuated. When the addition was completed, the temperature of the reactor was raised to 80 ° C., and the first reaction was performed at a speed of 150 rpm for 1 hour.

Subsequently, 1% by weight of 1,3-butylene glycol as a chain extender and 0.8% by weight of trimethylolpropane (TMP) as a crosslinking agent were sequentially added, followed by 0.1% by weight of di-N-butylbis(dodecylthio)tin as a catalyst. A secondary reaction was carried out for 30 minutes by adding wt%.

Subsequently, after reducing the temperature of the reaction vessel to 60 ° C., 15% by weight of toluene was added and stirred for 20 minutes, and 15% by weight of toluene was added and stirred for another 20 minutes.

Thereafter, the reaction was terminated while maintaining the temperature at 60° C., thereby preparing a urethane-based prepolymer.

Example 2

A urethane-based prepolymer was prepared in the same manner as in Example 1, except that polyethylene glycol having a weight average molecular weight of 400 g/mol was used instead of polypropylene glycol in Example 1.

Example 3

A urethane-based prepolymer was prepared in the same manner as in Example 1, except that sulfanilic acid sodium salt was used instead of 4-aminobenzoic acid sodium salt in Example 1.

Example 4

A urethane-based prepolymer was prepared in the same manner as in Example 1, except that sulfanilic acid sodium salt was used instead of 4-aminobenzoic acid sodium salt in Example 2.

Comparative Example 1

A urethane-based prepolymer was prepared in the same manner as in Example 1, except that the primary reaction was performed using polypropylene glycol instead of the mixture in which sodium aminobenzoic acid was dispersed in polypropylene glycol in Example 1.

Comparative Example 2

A urethane-based prepolymer was prepared in the same manner as in Example 1, except that the primary reaction was performed using polyethylene glycol instead of the mixture in which sodium aminobenzoic acid was dispersed in polyethylene glycol in Example 2.

Evaluation 1: physical properties of urethane-based prepolymer

The physical properties of the urethane-based prepolymers prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were measured in the following manner, and the results are shown in Table 1 below.

viscosity

Measured using a Brookfield viscometer.

importance

Specific gravity was measured using a cup.

heat resistance

Three specimens of KS C 2344 standard, 25 mm in width and 100 mm in length were individually measured and the average value was applied.

NCO group content

It was measured using the titration method.

adhesive strength

It was measured using a UTM instrument.

	Example 1	Example 2	Example 3	Example 4	Comparative Example 1	Comparative Example 2
Viscosity (cps)	1150	1200	1150	1260	6000	7000
importance	0.97	0.98	0.97	0.98	0.97	0.98
Heat resistance (℃)	210	190	205	198	130	140
NCO group content (% by weight)	3.15	3.18	3.12	3.2	7	8
Adhesion strength (kgf/cm 2 )	1.2	1.15	1.2	1.15	0.7	0.8

* In Table 1, the NCO group content (% by weight) is based on the total amount of urethane-based prepolymer

Through Table 1, it can be confirmed that the urethane-based prepolymers of Examples 1 to 4 prepared according to one embodiment are superior in heat resistance, adhesiveness, flowability, permeability and ionic conductivity compared to Comparative Examples 1 and 2. Accordingly, it is a binder for lithium secondary batteries requiring excellent adhesion and heat resistance, a separator coating agent for lithium secondary batteries requiring heat resistance and stability, and an interlayer material for sodium solid battery requiring heat resistance, mechanical stability and ion conductivity. It can be seen that it can be useful.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to make various modifications and practice within the scope of the claims and the detailed description of the invention and the accompanying drawings, and this is also the present invention. It goes without saying that it falls within the scope of the invention.

Claims (12)

1. Injecting and dissolving a diisocyanate-based compound in a reaction vessel;

   Injecting a mixture in which sodium salt is dispersed in polyol into a reaction vessel in which the diisocyanate-based compound is dissolved, and subjecting the mixture to a primary reaction;

   Injecting a chain extender, a crosslinking agent and a catalyst after the first reaction to perform a second reaction; and

   Injecting a solvent after the second reaction

   Method for producing a urethane-based prepolymer comprising a.
2. In paragraph 1,

   The diisocyanate-based compound is a method for producing a urethane-based prepolymer comprising methylene diphenyl diisocyanate, hexamethylene diisocyanate, or a combination thereof.
3. In paragraph 1,

   The polyol is a method for producing a urethane-based prepolymer comprising polyethylene glycol, polypropylene glycol, or a combination thereof.
4. In paragraph 3,

   The polyol is the polyethylene glycol,

   The weight average molecular weight of the polyethylene glycol is a method for producing a urethane-based prepolymer of 400 g / mol to 1,000 g / mol.
5. In paragraph 3,

   The polyol is the polypropylene glycol,

   The weight average molecular weight of the polypropylene glycol is a method for producing a urethane-based prepolymer of 1,000 g / mol to 5,000 g / mol.
6. In paragraph 1,

   The sodium salt is sulfanilic acid sodium salt, 4-aminobenzoic acid sodium salt, 2-aminobenzene-1,4-disulfonic acid sodium salt, 2-aminobenzene-1,4-dica A method for producing a urethane-based prepolymer comprising a sodium carboxylic acid salt, a hydrate thereof, or a combination thereof.
7. In paragraph 1,

   The urethane-based prepolymer is a method for producing a urethane-based prepolymer comprising an NCO group of 3.0% to 3.4% by weight.
8. In paragraph 1,

   The viscosity of the urethane-based prepolymer is a method for producing a urethane-based prepolymer of 1000 cps to 1500 cps.
9. In paragraph 1,

   The specific gravity of the urethane-based prepolymer is a method for producing a urethane-based prepolymer of 0.97 to 0.98.
10. In paragraph 1,

    The heat resistance of the urethane-based prepolymer is a method for producing a urethane-based prepolymer of 180 ° C to 220 ° C.
11. In paragraph 1,

    The adhesive strength of the urethane-based prepolymer is 1.1 kgf / cm ² to 1.5 kgf / cm ² with respect to the shear of the polyethylene film or polypropylene film. Method for producing a urethane-based prepolymer.
12. In paragraph 1,

    The urethane-based prepolymer is a method for producing a urethane-based prepolymer used in a binder for a lithium secondary battery, a separator coating agent for a lithium secondary battery, an interlayer for a sodium solid-state battery, or a combination thereof.

Images