阅读说明：本技术 一种长链不饱和羧酸或其衍生物改性的丙烯酸酯粘合剂及其制备方法和应用 (Acrylate adhesive modified by long-chain unsaturated carboxylic acid or derivative thereof, and preparation method and application thereof ) 是由 蔡小川 席柳江 刘龙 刘海明 黄梦琴 陈华丽 于 2019-10-31 设计创作，主要内容包括：本发明公开了一种长链不饱和羧酸或其衍生物改性的丙烯酸酯粘合剂及其制备方法和应用。本发明向丙烯酸酯粘合剂分子链中引入长链不饱和羧酸或其衍生物,所述的长链不饱和羧酸为碳链长度不小于12的不饱和羧酸,其衍生物为衍生的羧酸盐、酯、酰胺、酰卤或酸酐,所述的长链不饱和羧酸或其衍生物优选为油酸、蓖麻油酸或甘油酯。本发明选用以油酸、蓖麻油酸或甘油酯为代表的长链不饱和羧酸及其衍生物作为改性单体,原料简单易得,成本低廉,在保证良好的改性效果的前提下能够有效地控制原料成本,所得锂电池粘合剂兼具高粘接性、电解液耐受性、低吸水性和柔韧性等特点,对锂电池陶瓷隔膜浆料、负极浆料和正极浆料的制备要求均能够良好地匹配。(The invention discloses an acrylate adhesive modified by long-chain unsaturated carboxylic acid or derivatives thereof, and a preparation method and application thereof. The invention introduces long-chain unsaturated carboxylic acid or derivatives thereof into a molecular chain of an acrylate adhesive, wherein the long-chain unsaturated carboxylic acid is unsaturated carboxylic acid with the carbon chain length not less than 12, the derivatives thereof are derived carboxylate, ester, amide, acyl halide or anhydride, and the long-chain unsaturated carboxylic acid or the derivatives thereof are preferably oleic acid, ricinoleic acid or glyceride. According to the invention, long-chain unsaturated carboxylic acid represented by oleic acid, ricinoleic acid or glyceride and derivatives thereof are selected as modified monomers, the raw materials are simple and easy to obtain, the cost is low, the cost of the raw materials can be effectively controlled on the premise of ensuring a good modification effect, and the obtained lithium battery adhesive has the characteristics of high adhesion, electrolyte tolerance, low water absorption, flexibility and the like, and can be well matched with the preparation requirements of lithium battery ceramic diaphragm slurry, cathode slurry and anode slurry.)

1. The long-chain unsaturated carboxylic acid or derivative thereof modified acrylate adhesive is characterized in that the long-chain unsaturated carboxylic acid or derivative thereof is introduced into the molecular chain of the acrylate adhesive, the long-chain unsaturated carboxylic acid is unsaturated carboxylic acid with the carbon chain length not less than 12, and the derivative is derived carboxylate, ester, amide, acyl halide or anhydride.

2. The acrylate adhesive modified with a long-chain unsaturated carboxylic acid or its derivative according to claim 1, wherein the long-chain unsaturated carboxylic acid or its derivative is oleic acid, ricinoleic acid or glyceride.

3. The long-chain unsaturated carboxylic acid or its derivative modified acrylate adhesive according to claim 1, wherein the long-chain unsaturated carboxylic acid or its derivative accounts for 1 to 20% of the total amount of the monomers.

4. The method for preparing the long-chain unsaturated carboxylic acid or derivative modified acrylate adhesive according to any one of claims 1 to 3, wherein the long-chain unsaturated carboxylic acid or derivative modified acrylate adhesive is prepared by emulsion polymerization, and comprises the following steps:

(1) adding water, an initiator, an emulsifier and a water-soluble monomer into a reaction container, fully stirring to dissolve all components, and keeping stirring;

(2) dissolving long-chain unsaturated carboxylic acid or derivatives thereof in a water-insoluble monomer, stirring uniformly to form a homogeneous solution, injecting the homogeneous solution into a reaction container, and fully stirring to form a pre-emulsion;

(3) pre-emulsifying for 30-120 minutes, raising the reaction temperature to 65-80 ℃, reacting for 4-7 hours, cooling and collecting to obtain the finished adhesive.

5. The method for preparing the acrylate adhesive modified with the long-chain unsaturated carboxylic acid or the derivative thereof according to claim 4, wherein in the step (1), the initiator is one or more of persulfate or water-soluble azo initiator; the emulsifier is one or more than two of sodium dodecyl sulfate, SR-10, SE-10, SN-10 and OP-10; the water-soluble monomer is one or more than two of water-soluble unsaturated carboxylic acid, water-soluble unsaturated carboxylic ester and water-soluble unsaturated amide.

6. The method of claim 4, wherein the water-insoluble monomer is one or more of a water-insoluble unsaturated carboxylic acid ester and a water-insoluble vinyl monomer.

7. The method for preparing the long-chain unsaturated carboxylic acid or derivative modified acrylate binder of any one of claims 1 to 3, wherein the long-chain unsaturated carboxylic acid or derivative modified acrylate binder is prepared by solution polymerization, and comprises the following steps:

(a) adding solvent, initiator, long-chain unsaturated carboxylic acid or its derivative and monomer into a reaction vessel, stirring thoroughly to dissolve the components, and keeping stirring.

(b) And (3) raising the reaction temperature to 65-80 ℃, reacting for 4-7 hours, cooling and collecting the materials to obtain the finished product of the adhesive.

8. The preparation method of the long-chain unsaturated carboxylic acid or derivative modified acrylate adhesive according to claim 7, characterized by further comprising the steps of adding a neutralizing agent, and controlling the pH value of the finished adhesive to be 6-8; the neutralizer is alkali metal hydroxide, ammonia water or organic amine.

9. The method for preparing the long-chain unsaturated carboxylic acid or derivative modified acrylate binder of claim 7, wherein in the step (a), the monomer is one or more of water-soluble monomer water-soluble unsaturated carboxylic acid, water-soluble unsaturated carboxylic acid ester, and water-soluble unsaturated amide.

10. Use of the acrylate binder modified with a long chain unsaturated carboxylic acid or derivative thereof according to any one of claims 1 to 3 for ceramic separator bonding, negative electrode bonding or positive electrode powder bonding of lithium batteries.

Technical Field

The invention relates to a lithium battery adhesive, in particular to an acrylate adhesive modified by long-chain unsaturated carboxylic acid or derivatives thereof, and a preparation method and application thereof.

Background

At present, various new energy batteries represented by lithium ion batteries are widely applied in the fields of daily life and advanced science and technology. With the increasing demand of the market for new energy batteries, how to improve the production efficiency to expand the capacity on the premise of ensuring the safety and effectiveness of the batteries becomes a problem to be solved urgently for each large new energy battery manufacturer and its upstream suppliers. The main components of the battery comprise a shell, electrolyte, a positive electrode, a negative electrode, a diaphragm and the like, wherein the diaphragm, the negative electrode and the positive electrode which are used as core components of the battery all relate to the process steps of preparing powder materials into slurry and coating the slurry on the surface of a base material. The binder is one of indispensable components in the preparation of the slurry, and the quality thereof has a direct influence on the quality of the finished battery.

At present, the lithium battery separator, the negative electrode and the positive electrode adhesive in the market are common in acrylate adhesive, polyvinyl alcohol adhesive, styrene-butadiene latex adhesive and polyvinylidene fluoride adhesive. Among them, acrylate adhesives dominate due to their mature production process and diversified synthetic raw materials. However, acrylate binders also have certain drawbacks, such as poor toughness, high water absorption, and poor resistance to ester solvents, which adversely affect their use in lithium batteries. Therefore, modifying the acrylate adhesive to meet the use requirement of the lithium battery adhesive is always a popular research object in the field of lithium battery adhesives.

The long-chain unsaturated carboxylic acid and the derivative thereof represented by oleic acid, ricinoleic acid and glyceride of the oleic acid and the ricinoleic acid have great potential in the application direction of modification of the lithium battery adhesive of an acrylate system. This is because the long carbon chain of these materials, when copolymerized with an acrylate monomer, can impart the following properties to the product:

(1) good hydrophobicity;

(2) resistance to polar solvents such as ester solvents;

(3) the rigidity of the molecular chain is reduced, and the product shows good flexibility.

Disclosure of Invention

The invention aims to provide an acrylate adhesive modified by long-chain unsaturated carboxylic acid or derivatives thereof, and a preparation method and application thereof.

The technical scheme of the invention is as follows:

the long-chain unsaturated carboxylic acid or the derivative thereof is introduced into the molecular chain of the acrylate adhesive, the long-chain unsaturated carboxylic acid is unsaturated carboxylic acid with the carbon chain length not less than 12, the derivative is derived carboxylate, ester, amide, acyl halide or anhydride, and the long-chain unsaturated carboxylic acid or the derivative thereof is preferably oleic acid (cis-9-octadecenoic acid), ricinoleic acid (12-hydroxy-cis-9-octadecenoic acid) and glyceride thereof. The introduction of the long-chain unsaturated carboxylic acid or the derivative thereof can effectively improve the hydrophobicity and the solvent resistance of the adhesive, reduce the water absorption of slurry prepared by using the adhesive and the moisture residue after drying, improve the tolerance of the adhesive to the electrolyte environment, effectively improve the toughness of the adhesive, and the modified acrylate adhesive can be used for bonding a ceramic diaphragm, a negative electrode and positive electrode powder of a lithium battery.

Furthermore, the long-chain unsaturated carboxylic acid or the derivative thereof accounts for 1 to 20 percent of the total amount of the monomers.

The acrylate adhesive modified by the long-chain unsaturated carboxylic acid or the derivative thereof is prepared by emulsion polymerization, and specifically comprises the following steps:

(1) adding water, an initiator, an emulsifier and a water-soluble monomer into a reaction container, fully stirring to dissolve all components, and keeping stirring;

(2) dissolving long-chain unsaturated carboxylic acid or derivatives thereof in a water-insoluble monomer, stirring uniformly to form a homogeneous solution, injecting the homogeneous solution into a reaction container, and fully stirring to form a pre-emulsion;

(3) pre-emulsifying for 30-120 minutes, raising the reaction temperature to 65-80 ℃, reacting for 4-7 hours, cooling and collecting to obtain the finished adhesive.

Further, in the step (1), the initiator is one or more than two of persulfate or water-soluble azo initiator, preferably ammonium persulfate; the emulsifier is one or more than two of sodium dodecyl sulfate, SR-10, SE-10, SN-10 and OP-10, preferably SR-10; the water-soluble monomer is one or more than two of water-soluble unsaturated carboxylic acid, water-soluble unsaturated carboxylic ester and water-soluble unsaturated amide, preferably one or more than two of acrylic acid, methacrylic acid, acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate and polyethylene glycol acrylate.

In the step (2), the water-insoluble monomer is one or more of a water-insoluble unsaturated carboxylic acid ester and a water-insoluble vinyl monomer, and is preferably one or more of n-butyl acrylate, isooctyl acrylate, lauryl acrylate, isobornyl acrylate, methyl methacrylate, lauryl methacrylate, isobornyl methacrylate, styrene, and p-divinylbenzene.

The acrylate adhesive modified by the long-chain unsaturated carboxylic acid or the derivative thereof is prepared by a solution polymerization mode, and specifically comprises the following steps:

(a) adding solvent, initiator, long-chain unsaturated carboxylic acid or its derivative and monomer into a reaction vessel, stirring thoroughly to dissolve the components, and keeping stirring.

(b) And (3) raising the reaction temperature to 65-80 ℃, reacting for 4-7 hours, cooling and collecting the materials to obtain the finished product of the adhesive.

Further, adding a neutralizing agent, and controlling the pH value of the finished adhesive product to be 6-8; the neutralizing agent is alkali metal hydroxide, ammonia water or organic amine, preferably sodium hydroxide or lithium hydroxide.

In step (a), the monomer is a water-soluble monomer, and is one or more of water-soluble unsaturated carboxylic acid, water-soluble unsaturated carboxylic acid ester, and water-soluble unsaturated amide, preferably one or more of acrylic acid, methacrylic acid, acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, and polyethylene glycol acrylate.

The acrylate adhesive modified by the long-chain unsaturated carboxylic acid or the derivative thereof is used for bonding a ceramic diaphragm of a lithium battery, bonding a negative electrode or bonding positive electrode powder.

The experiment proves that:

(1) according to the lithium battery adhesive prepared by the emulsion polymerization or solution polymerization method, long-chain unsaturated carboxylic acid and derivatives thereof can be smoothly introduced into a molecular chain in a comonomer mode, and the obtained adhesive finished product has uniform appearance and does not have the defects of layering, precipitation and the like.

(2) After the adhesive is dried to form a film, the film is immersed in an electrolyte (mainly containing a carbonate solvent), and after the film is kept stand for 72 hours in an environment at 60 ℃, no remarkable volume and mass change is observed, so that the adhesive is proved to have good electrolyte tolerance.

(3) After the adhesive is dried to form a film, the film is immersed in pure water and is kept still at room temperature for 24 hours, no remarkable volume and mass change is observed, and the adhesive is proved to have low water absorption.

(4) The adhesive has high tensile strength, low modulus, flexible texture and good rebound resilience after being dried into a film.

(5) The adhesive has good adhesive force to materials such as polyolefin films, aluminum foils, copper foils and the like, and has good adhesive property to powder materials such as alumina powder ceramics, graphite, silicon-carbon cathode materials, lithium iron phosphate, ternary cathode materials and the like.

Compared with the prior art, the invention has the beneficial effects that:

(1) according to the invention, long-chain unsaturated carboxylic acid represented by oleic acid, ricinoleic acid or glyceride and derivatives thereof are selected as the modified monomers, the raw materials are simple and easy to obtain, the cost is low, and the cost of the raw materials can be effectively controlled on the premise of ensuring a good modification effect.

(2) The preparation method of the binder is simple, the binder is prepared by adopting an emulsion polymerization or solution polymerization method, the obtained lithium battery binder has the characteristics of high adhesion, electrolyte tolerance, low water absorption, flexibility and the like, the preparation requirements of the lithium battery ceramic diaphragm slurry, the negative electrode slurry and the positive electrode slurry can be well matched, and the binder has high universality.

Drawings

FIG. 1 is a DSC curve of the adhesive described in example 1. As can be seen from this curve, no significant glass transition characteristics were observed over the temperature range tested (-20 ℃ C. to 250 ℃ C.). The glass transition temperature of the adhesive is clearly below-20 ℃ in combination with the formulation of the adhesive, indicating that the adhesive has good flexibility at room temperature after drying.

Figure 2 is a TGA trace of the adhesive described in example 1. As can be seen from this graph, the initial thermal decomposition temperature of the binder was not lower than 400 ℃.

Fig. 3 shows the electrochemical cycling stability of the button cell of example 5, and it can be seen that the cell has a capacity retention rate higher than 90% after 100 cycles, and has good cycling performance.

Detailed Description

The present invention is described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.