WO2017200220A1 - Cellulose microfiber surface modified with associative copolymer, and thickener composition comprising same - Google Patents

Abstract

The present invention relates to a cellulose microfiber surface modified with an associative copolymer having a hydrophilic monomer and a hydrophobic monomer copolymerized, a method for producing same, and a thickener composition comprising same. The cellulose microfiber surface modified with an associative copolymer, according to the present invention, has excellent thickening capabilities by means of the mixed used of hydrophobic and hydrophilic groups, and exhibits a stable thickening effect regardless of high salinity and a change in pH.

Description

Cellulose microfibers surface-modified with associative copolymers and thickener compositions comprising the same

The present invention relates to a cellulose microfiber surface-modified with an associative copolymer copolymerized with a hydrophilic monomer and a hydrophobic monomer, a thickener composition comprising the same, and a method for preparing the same.

Generally, thickeners are included as additives for controlling workability and rheological properties in systems such as cosmetic compositions. Synthetic polymer thickener is used to enhance the viscosity of the composite fluid by increasing the viscosity of the system, preventing the separation of the water phase and the oil phase. As organic compounds, synthetic polymers such as acrylic acid polymers and carboxyvinyl polymers are used, and as inorganic compounds, montmorillonite, various clay minerals and silicas are used as thickeners. Recently, there is a growing trend around the world for environmentally friendly natural cosmetics, including the effects of synthetic surfactants, and there are organizations that certify organic / natural cosmetics, especially in Europe. In particular, the use of petroleum-derived PEG-added synthetic surfactants and synthetic polymer thickeners is becoming more stringent, and studies on natural polymers and natural thickeners that can replace them are being actively conducted.

Synthetic polymer thickener shows a uniform thickening effect due to the constant molecular weight and twisting of the polymer chain. It maintains a relatively stable aqueous phase even under various external conditions such as temperature changes, salt loading, and pH changes. Typically, carbomer is the most widely used, and most synthetic polymer thickeners including carbomer can be used as a thickener by dissolving or dispersing in water. Typically, 0.001 to 20 wt% of a thickener is added to the total weight of the cosmetic composition, and may be blended directly with the cosmetic composition or after dilution with water or a solvent to obtain a suitable viscosity. However, as the demand for hypo- and non-irritating products continues to increase, it is required not only to secure formulation stability through thickeners, but also to replace environment-friendly and natural raw materials in terms of differentiating the feeling of use and providing skin safety. There is a trend, and efforts for the technical development of such natural thickeners and surfactants have continued in the industry.

Recently, as the interest in eco-friendly and natural raw materials has increased in the general food industry including the cosmetics industry, there is a growing demand for natural thickeners that perform similar to conventional thickeners, but the thickeners based on synthetic polymers are still being replaced. Is not easy. Furthermore, conventional synthetic polymer thickeners use a large amount of organic solvents, chemical monomers, chemical initiators, polymerization inhibitors, and the like in the manufacturing process, and reuse a large amount of organic solvents in the process of removing and neutralizing unreacted monomers. These organics are not only classified as environmentally harmful, but also include the possibility of causing skin toxicity. In addition, when blending the existing synthetic polymer in the cosmetic composition, when prescribed in a certain concentration or more there is a problem that you will get an unsatisfactory feeling such as stiffness and stickiness when applying the skin. Although studies using xanthan gum and scleroglucan as natural materials are underway, there are disadvantages in that they do not exhibit the same thickening effect as conventional thickeners or have a poor feeling of use.

Korean Laid-Open Patent Publication No. 2001-0075666 relates to a mixture of an associative thickener and an aqueous protective coating composition, and discloses a hydrophobically modified cellulose derivative as an associative thickener. However, the disclosed cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl hydroxyethyl cellulose and the like have only a hydrophobic moiety on the surface of the cellulose, and thus do not show a large incremental effect.

Therefore, the present inventors introduced the associative copolymer by applying a polymer grafting technology to the surface of the cellulose to develop a synthesizing cellulose microfiber dispersion by oxidative reaction in order to develop a conventional synthetic thickener and other naturally occurring thickener. As a thickener thereof, the present invention was completed by confirming a very excellent effect.

(Patent Document 1) Korean Unexamined Patent Publication No. 2001-0075666

It is an object of the present invention to provide a cellulose microfiber surface-modified with an associative copolymer copolymerized with a hydrophilic monomer and a hydrophobic monomer.

Another object of the present invention is to provide a thickener composition comprising the cellulose microfibers.

Still another object of the present invention is to provide a cosmetic composition comprising the thickener composition.

It is another object of the present invention to provide a method for producing cellulose microfibers surface-modified with an associative copolymer.

The present invention provides cellulose microfibers surface-modified with associative copolymers copolymerizing hydrophilic monomers and hydrophobic monomers.

In addition, the present invention comprises the steps of: 1) grafting the associative copolymer on the surface of the cellulose by living radical copolymerization of a solution containing cellulose, hydrophilic monomers and hydrophobic monomers; And

2) a method of producing cellulose microfibers surface-modified with an associative copolymer, comprising the step of: oxidizing and adding a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical initiator to obtain cellulose microfibers. To provide.

The cellulose microfibers according to one embodiment of the present invention are surface-modified with an associative copolymer such that the cellulose microfibers form a gel phase. This three-dimensional microfiber gel phase not only exerts an excellent incremental effect due to strong hydration behavior, but also exhibits differentiated rheological behavior by physical interaction between the microfibers. The cellulose microfibers of the present invention are structurally stable and exhibit chemical resistance, flame resistance, and pH resistance, and provide differentiated usability, skin safety, and cosmetic formulation stability. Therefore, the thickener composition using the cellulose microfibers can be widely applied to the cosmetics market, such as cosmetic compositions, external application composition for the skin, and is expected to be highly utilized in various industries based on the composite fluid.

1 is a view showing a manufacturing process of the surface-modified cellulose microfibers with an associative copolymer according to an embodiment of the present invention.

Figure 2 shows the results of morphology confirmation of cellulose microfibers via TEM: (left) surface unmodified cellulose microfibers, (right) cellulose microfibers with poly (MPC-co-SMA) introduced.

FIG. 3 shows the results of the synthesis efficiency analysis of 2-methacryloyloxyethyl phosphorylcholine (MPC) and stearyl methacrylate (SMA) using ¹ H-NMR. The conversion rate of monomers present in the solvent during surface polymerization was confirmed: (left) (Right) ¹ H-NMR data after synthesis.

4 is a result of qualitative analysis using FT-IR to confirm the synthesis of MPC and SMA on the cellulose surface.

5 is a result of measuring the thickening effect of the cellulose microfiber dispersion surface-modified with an associative copolymer.

6 shows the results of rheological properties of cellulose microfiber dispersions surface-modified with associative copolymers: (A) elastic modulus, (B) viscous modulus, (C) shear stress, (D) yield by SMA content Stress.

FIG. 7 shows the results of flame resistance and pH resistance measurement of cellulose microfiber dispersions surface-modified with associative copolymers: (A) Unmodified microfiber dispersions (Neat CNFs) and surface modified microfiber dispersions (ACNFs). After the addition of 0, 1 or 1.5 M NaCl, the viscosity was measured to confirm the flame resistance. (B) Surface modified microfiber dispersions (Neat CNFs) and surface modified microfiber dispersions (ACNFs) were prepared at pH 2, 7 or 11 After adjusting the viscosity, the viscosity was measured to confirm the pH resistance.

One embodiment of the present invention provides a cellulose microfiber surface-modified with an associative copolymer copolymerized with a hydrophilic monomer and a hydrophobic monomer.

As used herein, the term "associative" means that two or more molecules of the same species have a property to combine (associate) with a loose regularity by combining by two or more intermolecular forces.

As used herein, the term "copolymerization" refers to a reaction of synthesizing a copolymer by mixing and polymerizing two or more monomers. When polymerizing two types of A and B monomers, a random copolymer is generally formed in which A and B are mixed irregularly, but a block copolymer having a structure in which A and B are regularly arranged according to the polymerization method ( A block copolymer or a grafted copolymer having a branch of B in a polymer of A may be generated.

In such embodiments, the "copolymer" may be a random copolymer, a block copolymer or a graft copolymer, for example, but may be a random copolymer, but is not necessarily limited thereto.

The term "hydrophilic monomer" refers to a monomer containing a hydrophilic functional group, and specifically, may be a zwitterionic monomer, anionic monomer, cationic monomer or nonionic monomer.

More specifically, the hydrophilic monomer may be any one of hydrophilic ethylenically unsaturated monomer, 2-methacryloyloxyethyl phosphorylcholine and betaine, or a mixture of two or more thereof. It is not limited.

The hydrophilic ethylenically unsaturated monomer may include acrylamide, methacrylamide, N-alkylacrylamide, vinyl sulfonic acid, styrene sulfonic acid, and the like, but is not limited thereto.

The "2-methacryloyloxyethyl phosphorylcholine (MPC)" is a biomimetic monomer having an amphoteric ion (zwitterion), and has excellent biocompatibility. Therefore, when the MPC is used as the hydrophilic monomer, it has excellent biocompatibility and can be safely used on the human body such as skin.

The term "betaine" refers to a molecule having an anion of quaternary ammonium and an acid (especially carboxylic acid) as a cation in one molecule, and has excellent biocompatibility.

The hydrophobic monomer may be C6 ~ C22 alkyl ester of acrylate or C6 ~ C22 alkyl ester of methacrylate, for example, C18 alkyl ester of methacrylate, that is, stearyl methacrylate. This is not restrictive.

The associative copolymer may have a content ratio of hydrophilic monomer and hydrophobic monomer of 1: 0.0001 to 1, specifically 1: 0.0001 to 0.1, more specifically 1: 0.0001 to 0.01, and more specifically 1: 0.001 to 0.01, more specifically 1: 0.005 to 0.01, and more specifically 1: 0.007 to 0.008, for example 1: 0.0075, but is not necessarily limited thereto. no.

The "surface modification" may mean that the associative copolymer is bonded to the surface of the cellulose microfibers, for example, may mean that the associative copolymer is grafted to the cellulose microfibers.

The cellulose microfiber may have a length of 10 to 5000 nm, but is not limited thereto.

The cellulose microfiber may have a thickness of 0.001 to 1000 nm, but is not limited thereto.

Another embodiment of the present invention provides a thickener composition comprising the cellulose microfibers.

The term "thickener" as used herein, also referred to as a thickener, thickener or thickener, refers to a substance that increases the viscosity of the solution.

The thickener composition may be a dispersion in which cellulose microfibers are dispersed in a solvent, but is not necessarily limited thereto, and the thickener composition may be prepared using a suitable method known in the art.

The thickener composition may have a viscosity of 1 to 1000000 Pa · s, and specifically, may have a viscosity of 1 to 100,000 Pa · s, but is not limited thereto.

The associative copolymer present on the surface of the cellulose microfibers may form a cellulose gel network by hydrophobic interaction with each other in the aqueous phase. This cellulose microfiber gel phase exhibits performance similar to that of conventional thickeners, as well as shear thinning under relatively low shear forces. When the shear force is removed, the initial viscosity is reversibly recovered, thereby giving a differentiated feeling. The thickener composition according to the embodiment is composed of a network of nm unit can be contained and permeable to the effective ingredients on the skin, but can protect the skin by preventing the transmission of harmful substances such as bacteria and dust outside the skin.

Another embodiment of the present invention provides a cosmetic composition comprising the thickener composition.

The thickener composition may include 0.001 to 50 parts by weight based on 100 parts by weight of the cosmetic composition, but is not necessarily limited thereto, and an appropriate amount may be selected according to the formulation, use, etc. of the cosmetic composition.

The cosmetic composition may have a moisturizing, atopic improvement effect by including the thickener composition.

The cosmetic composition according to the above embodiment is a fatty substance, an organic solvent, a dissolving agent, a gelling agent, a softening agent, an antioxidant, a suspending agent, a stabilizer, a foaming agent, a fragrance, a surfactant, water, an ionic or nonionic emulsifier. Cosmetics such as fillers, metal ion sequestrants, chelating agents, preservatives, vitamins, blockers, wetting agents, essential oils, dyes, pigments, hydrophilic or lipophilic actives, lipid vesicles or any other ingredients commonly used in cosmetics or It may contain adjuvants commonly used in the field of dermatology. Such adjuvants are introduced in amounts generally used in the cosmetic or dermatological arts.

The appearance of the cosmetic composition according to the above embodiment contains a cosmetically or dermatologically acceptable medium or base. These are all formulations suitable for topical application, for example, emulsions, suspensions, microemulsions, microcapsules, microgranules or ionic (liposomes) obtained by dispersing the oil phase in solutions, gels, solids, pasty anhydrous products, aqueous phases, and It may be provided in the form of a nonionic vesicle dispersant and these compositions may be prepared according to conventional methods in the art.

Cosmetics according to an embodiment of the present invention skin lotion, skin softener, skin toner, astringent, lotion, milk lotion, moisturizing lotion, nutrition lotion, massage cream, nutrition cream, moisturizing cream, hand cream, foundation, essence, nutrition essence , Pack, soap, cleansing foam, cleansing lotion, cleansing cream, body lotion, body cleanser, face wash, treatment, essence, beauty pack, ointment, gel, linen, liquid, patch and spray It is a formulation, but is not limited to a specific formulation, and may have a formulation of a conventional cosmetic composition.

Another embodiment of the present invention provides a method for producing cellulose microfibers surface-modified with an associative copolymer, the method comprising

1) grafting the associative copolymer on the surface of the cellulose by living radical copolymerization of a solution comprising cellulose, a hydrophilic monomer and a hydrophobic monomer; And

2) adding a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical initiator to oxidize to obtain cellulose microfibers.

The "cellulose" is a very abundant natural resource, can be supplied in large quantities, and the price is excellent. In addition, the cellulose molecule is structurally stable and can exhibit chemical resistance, flame resistance, and pH resistance.

The cellulose of step 1) may be obtained from wood, Korean paper, paper, cotton, hemp, plants, marine plants, etc., but is not necessarily limited thereto, and may be prepared using a conventional method for obtaining cellulose.

The cellulose of step 1) may be cellulose having a start site of a living radical polymerization reaction introduced on a surface thereof. Thus, the cellulose of step 1) can be prepared by a method comprising the following steps:

a) addition of 3-aminopropyltriethoxy silane to cellulose to prepare cellulose into which an amine group is introduced; And

b) adding trichloroacetyl isocyanate to cellulose into which the amine group is introduced to prepare cellulose into which trichloroacetyl group is introduced.

The trichloroacetyl group introduced in step b) may be an initiation site of living radical polymerization.

The cellulose of step 1) may be included in an amount of 1 to 15% by weight, specifically, 1 to 10% by weight, for example, 3 to 5% by weight, based on the total weight of the solution, but is not limited thereto. Do not.

The hydrophilic monomer of step 1) may be a zwitterionic monomer, an anionic monomer, a cationic monomer or a nonionic monomer.

More specifically, the hydrophilic monomer more specifically, the hydrophilic monomer is any one or a hydrophilic ethylenically unsaturated monomer, 2-methacryloyloxyethyl phosphorylcholine (beta) and betaine (betaine) thereof It may be a mixture of two or more, but is not limited thereto.

The hydrophilic ethylenically unsaturated monomer may include acrylamide, methacrylamide, N-alkylacrylamide, vinyl sulfonic acid, styrene sulfonic acid, and the like, but is not limited thereto.

The hydrophobic monomer of step 1) may be a cellulose microfiber which is a C6 to C22 alkyl ester of acrylate or a C6 to C22 alkyl ester of methacrylate, for example a C18 alkyl ester of methacrylate, namely stearyl methacryl Stearyl methacrylate, but is not limited thereto.

The solution of step 1) may further include a catalyst that can be used for living radical polymerization, and may further include, for example, molybdenum carbonyl (Mo (CO) ₆ ), but is not limited thereto.

The associative copolymer of step 1) may have a content ratio of the hydrophilic monomer and the hydrophobic monomer of 1: 0.0001 to 1, specifically 1: 0.0001 to 0.1, more specifically 1: 0.0001 to 0.01, It may be more specifically 1: 0.001 ~ 0.01, even more specifically 1: 0.005 ~ 0.01, even more specifically 1: 0.007 ~ 0.008, for example 1: 0.0075, but not necessarily It is not limited to this.

Cellulose is composed of fiber bundles, if not treated otherwise.When step 2) is carried out to convert the cellulose fiber bundles into microfibers having a thickness of several nanometers and a long axis of several microns, a clear gel phase is formed in the aqueous phase. Can form and have an increasing effect. The cellulose microfibers thus prepared exhibit an excellent incremental effect due to strong hydration behavior and may exhibit differentiated rheological behavior by physical interactions between the fibers.

Hereinafter, the present invention will be described in more detail in the following examples. However, the following examples merely illustrate the contents of the present invention and do not limit or limit the scope of the present invention. From the detailed description and examples of the present invention, those skilled in the art to which the present invention pertains can be easily inferred to be within the scope of the present invention.

Example 1 Preparation of Cellulose Microfibers Modified by Associative Copolymer

By following the method of <1-1> to <1-4> to prepare a cellulose microfiber surface-modified by the associative copolymer. The overall synthesis process is shown in FIG.

<1-1> Introduction of amine groups to the surface of cellulose

Cellulose with various fiber lengths and thicknesses was dispersed by fixation in toluene at 3 wt%. Then, to introduce an amine group, 150% of 3-aminopropyltriethoxy silane relative to the weight of cellulose was added and reacted with the hydroxyl group (-OH) on the surface of cellulose for 8 hours at 110 ° C. The cellulose into which the amine group (-NH ₂ ) was introduced was washed and recovered through repeated centrifugation.

<1-2> Trichloroacetyl group introduced to the cellulose surface

In order to introduce a starting site for living radical polymerization to cellulose, a condensation reaction of an amine group and trichloroacetyl isocyanate introduced on the surface of the cellulose particles was performed. To this end, the cellulose powder containing the amine group prepared in Example 1-1 was redispersed by irradiating toluene with ultrasonic waves at 35 ° C. for 10 minutes. At this time, the concentration of cellulose was fixed at 3 wt%. Trichloroacetyl isocyanate (50% of the weight of dispersed cellulose) is stirred with tributyltin dilaurate catalyst at 8O &lt; 0 &gt; C in an argon atmosphere for 8 hours to give trichloroacetyl to the surface The cellulose which introduce | transduced) group was synthesize | combined. The cellulose into which the trichloroacetyl group (-COCCl ₃ ) was introduced was washed and recovered through repeated centrifugation.

<1-3> Associative Polymer Chain Introduction Using Surface Polymerization

Cellulose powder having a polymerization initiator on the surface prepared in Example 1-2 was redispersed by irradiating ethanol at 35 ° C. for 10 minutes with ultrasonic waves. At this time, the concentration of cellulose was fixed at 3 wt%. Subsequently, 2-methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, and stearyl methacrylate (SMA) having a C18 hydrophobic chain were added to the dispersion. Molybdenum carbonyl (Mo (CO) ₆ ) was used as a catalyst and 0.05 wt% of the total weight was added. After argon was injected into the reactor to remove oxygen, polymer polymerization (living radical polymerization) was carried out at 70 ° C. for 12 hours to finally synthesize zwitterionic polymer and cellulose in which hydrophobic chains were introduced to the surface. It was. At this time, since MPC and SMA are randomly polymerized and introduced into the cellulose surface, MPC and SMA are randomly arranged in the main chain after synthesis.

<1-4> Cellulose microfiber dispersion through oxidation reaction

Cellulose polymerized on the surface prepared in Example 1-3 was redispersed in water through stirring at room temperature. At this time, the concentration of cellulose was fixed at 1 wt%. 10-30% NaBr by weight of the dispersed cellulose was added to the dispersion with a TEMPO (2,2,6,6-tetramethylpiperydine-1-oxylradical) catalyst and stirred for 10 minutes at room temperature. Subsequently, 1-15 mmol of NaClO was added, the pH of the reaction solution was titrated to 10 using 0.5 M NaOH, and stirred at 600 rpm for 4 hours at room temperature. Through this oxidation reaction, the remaining hydroxyl groups on the surface of cellulose were oxidized to carboxylic acid via aldehyde, and the cellulose fiber bundles were unwound in microfibrils to obtain cellulose microfibers.

Comparative Example 1 Preparation of Cellulose Microfiber Dispersion without Modified Surface

In order to compare the effect of the zwitterionic polymer introduced into the cellulose surface and the hydrophobic chain, a dispersion was prepared using only cellulose.

Specifically, cellulose was dispersed in water to prepare a cellulose microfiber dispersion having no surface modification.

Experimental Example 1 Confirmation of Introduction of Associative Polymer

The cellulose microfibers surface-modified with the associative polymer prepared in Example 1 and the cellulose microfibers with no surface-modified cellulose prepared in Comparative Example 1 were tested to confirm the introduction of the associative polymer.

Morphology of fibers chemically synthesized with poly (MPC-co-SMA) associative polymer on the surface of cellulose microfibers was confirmed by transmission electron microscopy (TEM) analysis (FIG. 2).

In addition, ¹ H-NMR analysis was performed to verify the synthesis efficiency of MPC and SMA. Specifically, in Example 1, the conversion rate of the monomer present in the solvent during the surface polymerization was analyzed. As a result, the synthesis efficiency of surface-modified cellulose microfibers using MPC and SMA was 70% (FIG. 3).

Further, qualitative analysis using Fourier Transform Infrared Spectrophotometer (FT-IR) confirmed that MPC and SMA were introduced into the surface of the cellulose microfiber prepared in Example 1 (FIG. 4).

Experimental Example 2 Viscosity Checking Experiment According to the SMA Ratio in Cellulose Microfibers

An experiment was performed to compare the degree of viscosity increase according to the SMA ratio introduced to the cellulose surface.

Specifically, the weight ratio of cellulose microfibers was 4 wt%, and all proceeded the same except for the variable values for each experiment. Preparation of cellulose microfibers surface-modified with an associative copolymer was carried out in the same manner as in Example 1 except for varying the ratio of MPC and SMA in the steps of Examples 1-3. Φ _SMA means the relative content ratio of _SMA to MPC. That is, the surface-modified cellulose microfibers are the experimental group (Φ _SMA = 0), MPC: SMA = 1: 0.005, the experimental group manufactured using only MPC without using SMA (Φ _SMA = 0.005), The viscosity was measured for the experimental group (Φ _SMA = 0.0075) prepared using the ratio of MPC: SMA = 1: 0.0075, the experimental group (Φ _SMA = 0.01) prepared using the ratio of MPC: SMA = 1: 0.01, Surface unmodified cellulose microfibers (Neat CNFs) of Comparative Example 1 were used as a control. Viscosity was measured by converting the shear stress according to the shear rate into viscosity using a rheometer (model name: DHR1) of TA. The experimental results for this are summarized in FIG. 5.

As can be seen in Figure 5, the viscosity of about 100-fold increase compared to the control by the introduction of hydrophobic association chain copolymerized with optimal SMA (Φ _SMA = 0.0075). In addition, at low shear rate conditions, the fibers formed a gel phase and showed a high viscosity. However, as the shear rate increased, the gel phase collapsed, and the sharp deduction was confirmed. Since hydrophobic interactions are expressed depending on the shear rate, reversible viscosity change can be confirmed.

<Experimental Example 3> Synthesis times using a rheometer Rheological confirmation of cellulose microfiber dispersions

Rheological confirmation of the effects of SMA content was carried out in the following manner. It was confirmed by comparing the modulus effect, flame resistance effect, pH resistance according to the SMA content.

The cellulose microfiber weight ratio was 4 wt%, and all proceeded the same except for the variable values for each experiment. Surface modified cellulose microfibers were prepared in the same manner as in Example 1 using MPC: SMA = 1: 0, 1: 0.005, 1: 0.0075 or 1: 0.01 ratios, respectively. Surface unmodified cellulose microfibers (Neat CNFs) prepared according to Comparative Example 1 were used as controls. The elastic modulus (storage modulus) was measured by converting the shear stress according to the strain (%) to the elastic modulus. The viscous modulus (loss modulus) was measured by converting the shear stress according to the strain (%) into viscous modulus. Shear stress was measured according to shear rate and shear strain. Yield stress was measured using the method of converting elastic modulus and viscous modulus. The measured elastic modulus is shown in FIG. 6A, the viscous modulus in FIG. 6B, the shear stress in FIG. 6C, and the yield stress in FIG. 6D.

As a result, it was confirmed that the cellulose microfibers of the present invention have excellent elasticity and viscosity, and in particular, the surface-modified cellulose microfibers prepared in an MPC: SMA = 1: 0.0075 content ratio had the best effect (FIG. 6).

Flame resistance and pH resistance measurement experiments were carried out in the following manner. Surface modified cellulose microfibers (Associative Cellulose Nano Fibers, ACNFs) were prepared in the same manner as in Example 1 using MPC: SMA = 1: 0.0075. Surface unmodified cellulose microfibers (Neat CNFs) prepared according to Comparative Example 1 were used as controls. In order to confirm flame resistance, after adding 0, 1 or 1.5 M NaCl to each microfiber dispersion, the viscosity according to the shear rate was measured in the same manner as in Experimental Example 2. In addition, in order to confirm the pH resistance, after adjusting each microfiber dispersion to pH 2, 7 or 11, the viscosity according to the shear rate was measured in the same manner as in Experiment 2. Flame resistance measurement results are shown in Figure 7A, pH resistance measurement results are shown in Figure 7B.

As a result, the cellulose microfibers of the present invention exhibited excellent flame resistance and pH resistance (FIG. 7). The cellulose microfiber gel phase associated by hydrophobic interaction can be interpreted as being able to maintain its own gel phase without being affected by the change in ion concentration.

From the above results, it was confirmed that the introduction of MPC and SMA in cellulose was successful, and rheologically verified the effect of the increase and viscosity through the SMA.

The thickener composition using the cellulose microfibers according to the present invention may be widely applied to the cosmetic market such as a cosmetic composition and a topical skin composition, and is expected to be highly applicable to various industries based on the complex fluid.

Claims (15)

A cellulose microfiber surface-modified with an associative copolymer obtained by copolymerizing a hydrophilic monomer and a hydrophobic monomer. The cellulose microfiber of claim 1, wherein the hydrophilic monomer is a zwitterionic monomer, an anionic monomer, a cationic monomer or a nonionic monomer. The cellulose fine according to claim 1, wherein the hydrophilic monomer is any one of hydrophilic ethylenically unsaturated monomer, 2-methacryloyloxyethyl phosphorylcholine and betaine, or a mixture of two or more thereof. fiber. The cellulose microfiber of claim 1, wherein the hydrophobic monomer is a C 6 -C 22 alkyl ester of acrylate or a C 6 -C 22 alkyl ester of methacrylate. The cellulose microfiber of claim 1, wherein the cellulose microfiber is 10-5000 nm in length. The cellulose microfiber of claim 1, wherein the cellulose microfiber has a thickness of 0.001 to 1000 nm. A thickener composition comprising the cellulose microfibers according to claim 1. The thickener composition of claim 7, wherein the thickener composition has a viscosity of 1 to 1000000 Pa · s. Cosmetic composition containing the thickener composition of Claim 7. 1) grafting the associative copolymer on the surface of the cellulose by living radical copolymerization of a solution comprising cellulose, a hydrophilic monomer and a hydrophobic monomer; And 2) a method of producing cellulose microfibers surface-modified with an associative copolymer, comprising the step of: oxidizing and adding a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) radical initiator to obtain cellulose microfibers. . The method of claim 10, wherein the cellulose of step 1) is obtained from wood, paper, paper, cotton, hemp, plant or marine plant. The method according to claim 10, wherein the cellulose of step 1) is cellulose having a start site of a living radical polymerization reaction introduced on a surface thereof. The method of claim 10, wherein the hydrophilic monomer of step 1) is a zwitterionic monomer, anionic monomer, cationic monomer or nonionic monomer. The cellulose fine according to claim 10, wherein the hydrophilic monomer is any one of hydrophilic ethylenically unsaturated monomer, 2-methacryloyloxyethyl phosphorylcholine, and betaine, or a mixture of two or more thereof. fiber. The method according to claim 10, wherein the hydrophobic monomer of step 1) is a C6 to C22 alkyl ester of acrylate or a C6 to C22 alkyl ester of methacrylate.

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