KR102213220B1 - Film including acetylated cellulose ether microfiber - Google Patents

Abstract

The film is started. The disclosed film contains acetylated cellulose ether microfibers and has a tensile strength of 50-150 MPa.

Description

Film including acetylated cellulose ether microfiber

The film is started. More specifically, a film comprising acetylated cellulose ether microfibers is disclosed.

Cellulose has three hydroxyl groups (-OH) per anhydroglucose unit, and some of these hydroxyl groups are substituted with a substituent such as an alkyl group to convert into a hydrophilic polymer, cellulose ether. In addition, the acetylated cellulose ether formed by introducing an acetyl group into the cellulose ether is widely used in a film for a separator.

However, a film for a separator made of acetylated cellulose ether has a problem in practicality because its tensile strength and durability are less than commercially required levels.

One embodiment of the present invention provides a film comprising acetylated cellulose ether microfibers.

One aspect of the present invention,

It provides a film containing acetylated cellulose ether microfibers and having a tensile strength of 50 to 150 MPa.

The film may have a tensile strength of 70 to 105 MPa.

The acetylated cellulose ether microfibers may have a diameter of 25 to 200 μm.

The film may further include more than 0 parts by weight to 100 parts by weight or less of acetylated cellulose ether based on 100 parts by weight of the acetylated cellulose ether microfibers.

The acetylated cellulose ether microfibers may be prepared from at least one acetylated cellulose ether selected from the group consisting of acetylated methylcellulose, acetylated hydroxypropylmethylcellulose, and acetylated hydroxyethylmethylcellulose.

The acetylated cellulose ether microfiber is mixed with an acetylated cellulose ether and a dispersion medium to prepare an acetylated cellulose ether suspension, and the acetylated cellulose ether suspension is introduced into a homogenizer having a nozzle having a diameter of 50 to 200 μm. And repeatedly passing the acetylated cellulose ether suspension through the nozzle 10 to 20 times while stirring at a pressure of 10,000 to 30,000 psi in the homogenizer.

The film may be a film for a separation membrane.

The film according to an embodiment of the present invention includes acetylated cellulose ether microfibers and thus has sufficient tensile strength to be used as a film for a separator.

Hereinafter, a film according to an embodiment of the present invention will be described in detail.

The film according to an embodiment of the present invention includes acetylated cellulose ether microfibers. In the present specification, "microfiber" refers to a fiber having a fine diameter of 1 to 1,000㎛.

The film has a tensile strength of 50 to 150 MPa. For example, the film may have a tensile strength of 70 to 105 MPa.

The acetylated cellulose ether microfibers are manufactured by processing acetylated cellulose ether.

Since the acetylated cellulose ether microfibers of the same weight prepared from a predetermined amount of acetylated cellulose ether have a larger surface area than the acetylated cellulose ether as a raw material, and the number of hydroxyl groups exposed to the surface is large, a plurality of acetylated cellulose ether microfibers are used. In the case of manufacturing a film, the plurality of acetylated cellulose ether microfibers are strongly bonded to each other by a plurality of hydrogen bonds to increase bonding strength. Accordingly, the film has excellent tensile strength.

The acetylated cellulose ether may have a degree of substitution of 1 to 2 alkyl groups (DS), a degree of substitution of 0 to 1 hydroxyalkyl groups (MS), and a degree of substitution of 1 to 2 acetyl groups (DS).

The acetylated cellulose ether may be formed by acetylation of a cellulose ether having an alkyl group substitution degree (DS) of 1 to 2 and a hydroxyalkyl group substitution degree (MS) of 0 to 1. Here, the alkyl group may have 1 to 16 carbon atoms. When preparing the acetylated cellulose ether, cellulose may be used as a starting material, or cellulose ether having the above degree of substitution (DS, MS) range may be used.

When the cellulose ether having the degree of substitution of the alkyl group (DS) and the degree of substitution of the hydroxyalkyl group (MS) is acetylated, it is not soluble in water, but is well soluble in an organic solvent such as acetone, and has a high molecular weight and thus mechanical strength It is possible to obtain an excellent acetylated cellulose ether.

The acetylated cellulose ether may be formed by acetylating at least one cellulose ether selected from the group consisting of methylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose.

In addition, the viscosity of the solution obtained by dissolving the acetylated cellulose ether in acetone (the concentration of the acetylated cellulose ether: 2% by weight) is 5 to 100,000 cps, as measured by a Brookfield viscometer at 20° C. and 20 rpm. I can. When the viscosity is within the above range, the mechanical strength of the acetylated cellulose ether is excellent.

The acetylated cellulose ether may have a melting point of 180 to 250°C. If the melting point is within the above range, the acetylated cellulose ether may be applied to melt processing such as injection.

Hereinafter, a method for preparing the acetylated cellulose ether will be described in detail.

First, cellulose ether is prepared by etherifying the hydroxyl group of cellulose. That is, by the etherification reaction of cellulose, some of the hydroxyl groups in the cellulose structure are blocked, or hydrogen in the hydroxyl groups is substituted with another substituent to form a cellulose ether. At this time, the main chain of the cellulose is maintained without being cut, but the hydrogen bonds in the cellulose are broken to convert the cellulose into an amorphous structure, so that a water-soluble cellulose ether having a high molecular weight is obtained. Then, the hydrogen atom in the hydroxyl group contained in the water-soluble cellulose ether prepared above acetyl group (CH ₃ CO ^-) and substituted with the prepared (this replacement reaction, acetylation ") water-insoluble cellulose ether acetylation. In Formulas 1 and 2 below, anhydroglucose, a basic repeating unit of cellulose, is sequentially etherified and acetylated to convert it into a basic repeating unit of acetylated cellulose ether.

[Formula 1]

[Formula 2]

Formula 1 shows a process in which cellulose is etherified to convert to hydroxyalkylalkyl cellulose, and then the hydroxyalkylalkyl cellulose is acetylated to convert to acetylated cellulose ether, and in Formula 2, cellulose is etherified to After conversion to alkyl cellulose, the alkyl cellulose is acetylated to show the process of conversion to acetylated cellulose ether.

In Formula 1, R ₁ and R ₂ may be, independently of each other, H, CH ₃ , CH ₂ CH ₂ OH or CH ₂ CH(CH ₃ )OH, and R ₃ may be H or CH ₃ .

In Formula 2, R ₄ and R ₅ may each be H or CH ₃ , and at least one of R ₄ and R ₅ may be CH ₃ .

In the present specification, the degree of substitution (DS) means the average number of hydroxyl groups substituted with an alkyl group per anhydroglucose unit. Since there are at most 3 hydroxyl groups per anhydroglucose unit, when substituted with a monofunctional substituent, the theoretical maximum degree of substitution (DS) is 3. However, since the polyfunctional or polymerizable substituent reacts not only with hydrogen of the hydroxyl group contained in the anhydroglucose unit, but also with itself, the degree of substitution (DS) is not limited to 3. In addition, in the present specification, the degree of substitution (MS) refers to the number of moles of a polyfunctional or polymerizable substituent per anhydroglucose unit. There is no theoretical maximum of this degree of substitution (MS).

In the acetylated cellulose ether according to an embodiment of the present invention, hydrogen in most hydroxyl groups present in the cellulose ether may be substituted with an acetyl group, which is a hydrophobic group. Therefore, the acetylated cellulose ether is not soluble in water, but has a property of soluble in organic solvents.

The acetylated cellulose ether microfibers may have a diameter of 25 to 200 μm. When the diameter of the acetylated cellulose ether microfibers is within the above range, the acetylated cellulose ether microfibers are not only easy to manufacture, but may have excellent strength.

The film may further include more than 0 parts by weight to 100 parts by weight or less of acetylated cellulose ether based on 100 parts by weight of the acetylated cellulose ether microfibers. When the content of the acetylated cellulose ether is within the above range, the tensile strength of the film may be increased while manufacturing cost may be reduced.

The acetylated cellulose ether further included in the film may have a diameter of 0.05 to 7 mm. The acetylated cellulose ether further included in the film may be a raw material for the acetylated cellulose ether microfibers.

The acetylated cellulose ether microfibers may be prepared from at least one acetylated cellulose ether selected from the group consisting of acetylated methylcellulose, acetylated hydroxypropylmethylcellulose, and acetylated hydroxyethylmethylcellulose.

Hereinafter, a method for preparing the acetylated cellulose ether microfibers will be described in detail.

First, the acetylated cellulose ether and the dispersion medium are mixed to prepare an acetylated cellulose ether suspension. Subsequently, the acetylated cellulose ether suspension is introduced into a homogenizer having a nozzle having a diameter of 50 to 200 μm. Thereafter, the acetylated cellulose ether suspension is repeatedly passed through the nozzle 10 to 20 times while stirring at a pressure of 10,000 to 30,000 psi in the homogenizer to prepare acetylated cellulose ether microfibers.

The dispersion medium may include alcohol such as ethanol.

The acetylated cellulose ether suspension may have a concentration of 1.0 to 5.0% by weight of acetylated cellulose ether.

The acetylated cellulose ether suspension that has passed through the nozzle of the homogenizer is re-introduced into the homogenizer through a conveying line until the target number of passes is reached.

The film may be a film for a separation membrane. For example, the film may be a film for a water treatment membrane, a film for a separator for secondary battery, or a film for a gas separator membrane.

Hereinafter, a method of manufacturing the film will be described in detail.

First, the acetylated cellulose ether microfibers are dissolved in an organic solvent such as dimethylformamide to prepare a film preparation solution. Then, the film preparation solution is applied to a substrate such as a glass substrate. Thereafter, the substrate on which the film preparation solution is applied is dried to prepare a film.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example

Manufacturing example One: Acetylation Preparation of cellulose ether

In a 3L reactor equipped with a stirrer, hydroxypropylmethylcellulose (Samsung Fine Chemical, PMA15M, methyl group substitution degree (DS): 1.84, hydroxypropyl group substitution degree (MS): 0.25) 200 g, acetic acid 1400 g, sodium acetate 300 g, and After adding 600 g of acetic anhydride, the mixture was reacted at 85° C. for 8 hours while stirring at 200 rpm to prepare acetylated cellulose ether. At this time, acetic acid was used as a solvent, and sodium acetate was used as a catalyst. Subsequently, the reactor contents were sprayed into an 18L coagulating bath to solidify, washed 5 times with clean water, and dried.

Manufacturing example 2: Acetylation Preparation of cellulose ether microfibers

The acetylated cellulose ether prepared in Preparation Example 1 was mixed with ethanol to prepare an acetylated cellulose ether suspension having a concentration of 3% by weight. Subsequently, the acetylated cellulose ether suspension was introduced into a homogenizer (CAT Gmbh, X1740) equipped with a nozzle having a diameter of 150 μm. Thereafter, the acetylated cellulose ether suspension was stirred at a pressure of 20,000 psi in the homogenizer. During the stirring, the acetylated cellulose ether suspension was passed through the nozzle, and then immediately re-introduced into the homogenizer was repeated 15 times. As a result, acetylated cellulose ether microfibers having a diameter of 140 μm were obtained.

Example 1-4 and Comparative example 1: Preparation of the film

The acetylated cellulose ether (ACE) prepared in Preparation Example 1 and the acetylated cellulose ether microfibers (ACE MF) prepared in Preparation Example 2 were mixed in the ratio shown in Table 1 below to obtain a film preparation mixture. Thereafter, 5 g of the film preparation mixture was dissolved in 95 g of dimethylformamide (DMF) and stirred for 2 hours to prepare a film preparation solution. Thereafter, 10 g of the film preparation solution was collected, applied to a thickness of 5 mm on a glass substrate, and dried in a vacuum oven for 60 minutes. At this time, the temperature of the vacuum oven was maintained at 30°C, and the thickness of the final dried film was 0.2±0.02mm. In addition, the viscosity of the film preparation solution was measured with a Brookfield viscometer at 20° C. and 20 rpm, and the results are shown in Table 1 below.

Example Comparative example One 2 3 4 One ACE MF
(Part by weight) 30 50 70 100 0 ACE
(Part by weight) 70 50 30 0 100 Viscosity
(cps) 700 590 430 350 500

Evaluation example

Evaluation example : Of film The tensile strength evaluation

The tensile strength of each film prepared in Examples 1 to 4 and Comparative Example 1 was measured according to ASTM D882, and the results are shown in Table 2 below.

Example Comparative example One 2 3 4 One The tensile strength
(MPa) 70 75 89 105 36

Referring to Table 2, it was found that each film prepared in Examples 1 to 4 had higher tensile strength than the film prepared in Comparative Example 1.

The present invention has been described with reference to the embodiments, but these are merely exemplary, and those of ordinary skill in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (7)

Contains acetylated cellulose ether microfibers, has a tensile strength of 50 to 150 MPa,
The acetylated cellulose ether microfibers,
Preparing an acetylated cellulose ether suspension by mixing the acetylated cellulose ether and a dispersion medium;
Injecting the acetylated cellulose ether suspension into a homogenizer having a nozzle having a diameter of 50 ~ 200㎛; And
In the homogenizer, the acetylated cellulose ether suspension is stirred at a pressure of 10,000 to 30,000 psi while repeatedly passing through the nozzle 10 to 20 times. The method of claim 1,
The film is a film having a tensile strength of 70 ~ 105MPa. The method of claim 1,
The acetylated cellulose ether microfiber is a film having a diameter of 25 ~ 200㎛. The method of claim 1,
A film further comprising more than 0 parts by weight to 100 parts by weight or less of acetylated cellulose ether based on 100 parts by weight of the acetylated cellulose ether microfibers. The method of claim 1,
The acetylated cellulose ether microfiber is a film made from at least one acetylated cellulose ether selected from the group consisting of acetylated methylcellulose, acetylated hydroxypropylmethylcellulose, and acetylated hydroxyethylmethylcellulose. delete The method according to any one of claims 1 to 5,
The film is a film for a separation membrane.