阅读说明：本技术 透明性优秀的再生纤维素面膜片及其制备方法 (Regenerated cellulose facial mask with excellent transparency and preparation method thereof ) 是由 李权宣 崔富琪 李昇官 金巠学 于 2020-08-20 设计创作，主要内容包括：本发明涉及透明性优秀的再生纤维素面膜片及其制备方法,其特征在于,将再生纤维素无纺布浸渍在碱溶液中进行填充,并与羧甲基化剂反应来制备,由上述羧甲基化剂反应得到的再生纤维素无纺布的透明度通过利用明暗度差的透明度测定实验,满足如下式1。(其中,d1为明暗度底板(黑色点),d2为明暗度背景(白色背景。))式1：100≤d2-d1。(The present invention relates to a regenerated cellulose facial patch having excellent transparency and a method for producing the same, wherein a regenerated cellulose nonwoven fabric is impregnated with an alkaline solution and filled with the alkaline solution, and the regenerated cellulose nonwoven fabric is reacted with a carboxymethylating agent, and the transparency of the regenerated cellulose nonwoven fabric obtained by the carboxymethylating agent reaction satisfies the following formula 1 in a transparency measurement experiment using a difference in brightness and darkness. (where d1 is a shading base plate (black dot) and d2 is a shading background (white background)) formula 1: d2-d1 is more than or equal to 100.)

1. A regenerated cellulose facial mask sheet with excellent transparency is characterized in that a regenerated cellulose nonwoven fabric prepared by immersing and filling a regenerated cellulose nonwoven fabric in an alkaline solution and reacting with a carboxymethylating agent satisfies the following formula 1 through a transparency measurement experiment calculated by the following formula 1 using the difference of brightness,

formula 1: d2-d1 of more than or equal to 100

(wherein d1 is a shading base plate (black dot) and d2 is a shading background (white background)).

2. The regenerated cellulose facial mask sheet with excellent transparency according to claim 1, characterized in that the non-woven fabric for facial mask has a bi-directional property and 25 to 70g/m²The weight of (c).

3. The regenerated cellulose facial film excellent in transparency according to claim 1, characterized in that,

the regenerated cellulose face film sheet used in the reaction satisfies tensile strength elongation equivalent to the following range,

(in the case of MD, tensile strength (kg/m)²)6.0 to 12.0, an elongation (%) of 10 to 45, and a tensile strength (kg/m) in terms of CD²)4.0 to 12.0, and an elongation (%) of 10 to 45).

4. The regenerated cellulose facial mask sheet having excellent transparency according to claim 1, characterized in that the degree of substitution of carboxymethyl group of the facial mask nonwoven fabric sheet has a value of 0.05 to 0.3.

5. The regenerated cellulose facial film excellent in transparency according to claim 1, characterized in that,

the mask non-woven fabric sheet satisfies tensile strength elongation equivalent to the following range after reaction,

(in the case of MD, tensile strength (kg/m)²)6.0 to 12.0, an elongation (%) of 10 to 45, and a tensile strength (kg/m) in terms of CD²)4.0 to 12.0, and an elongation (%) of 10 to 45).

6. A method for producing a regenerated cellulose facial film sheet having excellent transparency, comprising:

(a) a step of dipping the regenerated cellulose non-woven fabric in an alkali solution for pretreatment;

(b) a step of pressing the pretreated regenerated cellulose nonwoven fabric;

(c) a step of preparing a reaction solution by dissolving a carboxymethylating agent in water;

(d) adding the extruded cellulose nonwoven fabric to the reaction solution, and substituting a hydroxyl group at the end of the regenerated cellulose nonwoven fabric with a carboxymethyl group; and

(e) a step of compressing the substituted regenerated cellulose nonwoven fabric and then drying the compressed nonwoven fabric.

Technical Field

The present invention relates to a regenerated cellulose facial mask sheet having excellent transparency and a method for preparing the same, and more particularly, to a facial mask sheet product which can greatly improve the transparency of a skin beauty mask to further satisfy the product excellence, and a method for preparing the same.

Background

The facial mask is applied on skin surface, and removed for supplying water, oil and nutrition contained in the facial mask to skin.

Conventional face masks are produced by using polypropylene, polyethylene terephthalate, cellulose-based materials, and the like alone or by mixing them.

Among them, a mask sheet made of a synthetic material such as polypropylene or polyethylene terephthalate has a low ability to adhere to the skin and to moisturize the skin, and thus has a drawback of having a low ability to deliver functional active ingredients related to moisture retention, sedation, and elasticity to the skin.

In contrast, regenerated cellulose fibers are environmentally friendly polymers having a chemical structure derived from natural cotton fibers or the like, and a plurality of cellulose monomer molecules are aggregated to form fibers. Regenerated cellulose fibers are composed of crystalline and amorphous regions, and when immersed in water, the liquid permeates into the amorphous regions and swells. From such properties, a mask sheet using regenerated cellulose fibers is considered to have excellent skin-friendly properties and moisturizing properties.

However, as expensive materials having water-replenishing property and transparency such as hydrogel are developed, regenerated cellulose fibers are limited in exhibiting high transparency at a level required by consumers. Nevertheless, there is a continuing need for regenerated cellulose fibers that are both natural and cost effective.

Therefore, the present applicant filed korean patent application No. 10-2019-0054472, "title of the invention: a mask sheet product using a low-substituted carboxymethyl cellulose non-woven fabric and a preparation method thereof. The present invention relates to a mask sheet which satisfies water-replenishing property and can improve productivity at low cost.

However, the characteristics required for a facial film sheet are not only water-replenishing properties but also transparency that can satisfy the aesthetic properties of the product, and consumers are increasing.

Therefore, it is necessary to develop a regenerated cellulose facial film satisfying transparency and having excellent cost performance.

Documents of the prior art

Patent document

KR10-2015-0050808

KR10-2015-0008644

KR10-2019-

KR10-2013-0134423

KR10-2018-0073172

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a regenerated cellulose facial film sheet satisfying transparency, and a method for producing the same.

Another object of the present invention is to provide a method for producing a mask sheet product, which can improve transparency and control the concentration of a carboxymethylating agent for adjusting the tensile strength elongation, which is a physical property for maintaining the product form of the mask sheet.

The nonwoven fabric sheet for a low-substituted carboxymethyl cellulose facial mask according to an embodiment of the present invention for achieving the above object is characterized by satisfying the following formula 1 in a transparency measurement test using a difference in brightness in a state immersed in water.

Formula 1: d2-d1 of more than or equal to 100

And the carboxymethyl substitution degree of the cellulose facial mask sheet is equivalent to 0.05-0.3.

The present invention for achieving the above object is prepared by immersing and filling a regenerated cellulose nonwoven fabric in an alkaline solution and reacting the cellulose nonwoven fabric with a carboxymethylating agent.

And, includes: (a) a step of immersing a regenerated cellulose nonwoven fabric in an alkaline solution to perform pretreatment, (b) a step of squeezing the pretreated cellulose nonwoven fabric, (c) a step of dissolving a carboxymethylating agent in water to prepare a reaction solution, (d) a step of adding the squeezed cellulose nonwoven fabric to the reaction solution to substitute a hydroxyl group at an end of the regenerated cellulose nonwoven fabric with a carboxymethyl group and substitute the hydroxyl group with a carboxymethyl substitution degree of 0.05 to 0.3, and (e) a step of compressing the substituted cellulose nonwoven fabric and then drying the compressed cellulose nonwoven fabric.

The mask sheet of the present invention constituted and operated as described above has advantages: the transparency is greatly improved, and the use satisfaction can be greatly improved when the mask is attached to the face.

As a result, the nonwoven fabric for a low-substituted carboxymethyl cellulose facial mask having excellent transparency and the method for preparing the same according to the present invention can be used in various materials and weights due to excellent transparency, and thus, the range of use of facial mask essence may be widened.

In addition, the nonwoven fabric for a low-substituted carboxymethyl cellulose facial mask having excellent transparency and the method for preparing the same according to the present invention have an advantage of being capable of preparing various products because of the cellulose-based nonwoven fabric whose safety and efficacy in use are verified.

Drawings

FIG. 1 is a flow chart showing a process for producing a cellulose facial film sheet excellent in transparency according to the present invention,

FIG. 2 is a detailed flowchart of the method for preparing a cellulose facial film sheet having excellent transparency according to the present invention,

FIG. 3 is a view showing a transparency test apparatus for a cellulose facial film sheet excellent in transparency according to the present invention,

FIG. 4 is a graph showing the analysis result by the transparency test apparatus of the cellulose facial film sheet excellent in transparency according to the present invention,

FIG. 5 is an image showing the transparency test of examples 1 to 4 of the present invention,

fig. 6 is an image showing a transparency test of comparative examples 1 to 4 of the present invention.

Detailed Description

The advantages and features of the present invention, as well as methods of accomplishing the same, will become apparent from the following detailed description of the embodiments when read in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and the embodiments are provided to complete the disclosure of the present invention and to fully inform the scope of the present invention to those skilled in the art to which the present invention pertains, and the present invention is defined only by the scope of the claims. Like reference numerals appearing throughout the specification denote like structural elements.

Hereinafter, the regenerated cellulose facial film sheet having excellent transparency and the method for producing the same according to the present invention will be described in detail with reference to the drawings.

The regenerated cellulose facial mask with excellent transparency is prepared by soaking and filling regenerated cellulose non-woven fabrics in alkaline solution and reacting with carboxymethylating agent.

Among them, the regenerated cellulose facial mask sheet is characterized by satisfying the following formula 1 by a transparency measurement experiment using a difference in brightness in a state immersed in water, and is characterized by preparing a facial mask sheet having a very excellent satisfaction as a main technical gist.

Formula 1: d2-d1 of more than or equal to 100

Also, a method for preparing a mask sheet according to the present invention includes: (a) a step of immersing a cellulose nonwoven fabric in an alkaline solution to perform pretreatment, (b) a step of squeezing the pretreated cellulose nonwoven fabric, (c) a step of dissolving a carboxymethylating agent in water to prepare a reaction solution, (d) a step of adding the squeezed cellulose nonwoven fabric to the reaction solution to substitute a hydroxyl group at an end of the cellulose nonwoven fabric with a carboxymethyl group and substitute the hydroxyl group with a carboxymethyl group substitution degree of 0.05 to 0.3, and (e) a step of compressing the substituted cellulose nonwoven fabric and then drying the compressed cellulose nonwoven fabric.

The invention can prepare a reaction solution for dissolving a carboxymethylating agent in water and prepare a mask sheet product with a carboxymethyl substitution degree of 0.05-0.3 of cellulose non-woven fabric by controlling the concentration of the reaction solution.

Fig. 1 is a flowchart illustrating a method for manufacturing a mask sheet product using a regenerated cellulose nonwoven fabric having excellent transparency according to the present invention, and fig. 2 is a detailed flowchart.

As shown in the drawing, the method for preparing a mask sheet having excellent transparency according to the present invention comprises: a step of dipping in an aqueous alkali solution for pretreatment (S10), a step of pressing (S20), and a step of reacting the cellulose nonwoven fabric with a carboxymethylating agent (S30).

Referring to fig. 2, in more detail, it includes: the method comprises a step (S100) of pretreating the cellulose nonwoven fabric by immersing it in an alkaline solution, a step (S200) of pressing, a step (S300) of preparing a reaction solution by dissolving a carboxymethylating agent in water, a step (S400) of substituting the pressed cellulose nonwoven fabric by adding it to the reaction solution, and a step (S500) of compressing and drying the resultant product to complete the mask sheet.

< step (S100) of pretreating a cellulose nonwoven fabric by immersing it in an alkali solution >

The step is a process of immersing the cellulose non-woven fabric in an alkali solution and curing to smoothly realize a reaction process. If the pretreatment process is not sufficiently performed, substitution reaction and the like do not occur, and thus the pretreatment process is very important. The pretreatment process needs to be carefully adjusted because the fabric properties will change depending on the temperature and time of the pretreatment process.

The nonwoven fabric for a mask used in the present invention is characterized by being a regenerated cellulose-based nonwoven fabric for a mask having a bi-directional property and a weight of 25 to 70g/m 2.

The alkali solution for impregnating the cellulose non-woven fabric has a concentration of 15 to 40%. The alkali solution may be mixed with one or more chemical substances having a strong alkali such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonia (NH4OH), or Trimethyl ammonium hydroxide (Trimethyl ammonium hydroxide). Among them, sodium hydroxide is preferably used as the alkali solution.

When the concentration of the above-mentioned alkali solution is less than 15%, it is difficult to obtain a desired substitution degree due to low basicity. On the other hand, if the alkali solution concentration is more than 40%, the degree of substitution is excessively increased or side reactions are frequently generated due to an increase in the degree of reaction with the carboxymethyl solution, which may result in deterioration of the physical properties of the fabric.

The cellulose nonwoven fabric is soaked in an alkali solution and then subjected to a curing process. The curing is a process for dissociating hydrogen bonds of cellulose molecules, and is usually performed at a temperature of 20-70 ℃. When the temperature is lower than 20 ℃, too much time is required for proper aging. When the temperature exceeds 70 ℃, excessive reaction occurs more and embrittlement of the fiber may be caused. And also to adjust the time of maturation.

The aging time varies depending on the compounding ratio, the dipping time, the aging temperature, and the characteristics of the equipment, and therefore, it is preferable to finally optimize the degree of substitution of the nonwoven fabric by measurement.

< extrusion (squeezing) step (S200) >

Subsequently, the cured cellulose nonwoven fabric is appropriately pressed by two rolls with pressure adjusted.

The pressing step is a very important element for determining the amount of alkaline solution remaining in the nonwoven fabric by leaving only a desired portion of the alkaline solution used in the aging from the cellulose nonwoven fabric and removing the remaining amount. In terms of extrusion, the material distribution taking rate is determined by adjusting the pressure between rollers, and the material taking rate is preferably 200-500% as a material taking rate standard. The above take-out rate (%) represents the ratio of the amount of the alkali solution remaining in the impregnated cellulose nonwoven fabric to the dry weight of the cellulose nonwoven fabric.

Namely, the take-out rate (%) was (wet-dry weight)/dry weight × 100.

When the extraction rate is less than 200%, the hydrogen bond dissociation of the cellulose molecule is insufficient and it may be difficult to adjust the degree of substitution. On the contrary, when the extraction rate is more than 500%, hydrogen bonds of cellulose molecules are excessively dissociated and a high degree of substitution may occur.

Therefore, it is important to properly adjust the extrusion so that the rate of taking out the alkali solution from the cellulose non-woven fabric is 200-500%.

< step (S300) of preparing a reaction solution by dissolving a carboxymethylating agent in water >

After aging, the carboxymethylating agent is dissolved in water to prepare a reaction solution.

The carboxymethylating agent is a chemical capable of substituting carboxymethyl group in the cellulose nonwoven fabric, and a halogenated acetic acid such as monochloroacetic acid, monobromoacetic acid, monoiodoacetic acid, or a neutralized product thereof can be used.

The carboxymethylating agent is the most important element for determining the degree of substitution, and preferably, the carboxymethylating agent is dissolved in water in an amount of 20 to 60 weight percent based on 40 to 80 weight percent to prepare a reaction solution. When the amount of the reaction solution added is less than 20% by weight, there is a problem that the degree of substitution is lowered, and when it exceeds 60% by weight, excessive substitution may occur.

In order to prevent side reactions, distilled water, ion-exchanged water, or ro (reverse osmosis) water (water filtered by reverse osmosis) from which metal components causing side reactions are removed can be used as the water used. When the metal content in the used water is more than 50ppm, side reactions may occur. Wherein the metal can be calcium, magnesium, iron, copper, etc.

< step (S400) of adding extruded cellulose nonwoven Fabric to reaction solution for substitution >

The extruded cellulose nonwoven fabric was put into the prepared reaction solution, and the resultant was re-impregnated and heat-treated to carry out substitution reaction. In this case, the extruded cellulose nonwoven fabric and the reaction solution are preferably mixed so that the weight ratio is 1:2 to 1:8, and more preferably 1:4 to 1: 6. When the content of the reaction liquid to the extruded cellulose nonwoven fabric is less than 2 times, the content of the reaction liquid is insufficient, and a low substitution reaction rate occurs. On the contrary, when the content of the reaction solution is more than 8 times, there is a problem that the side reaction rate is increased.

The substitution reaction can be initiated by heat treatment at 70-150 ℃, and when the temperature is lower than 70 ℃, the substitution degree is low, and when the temperature is higher than 150 ℃, the fiber is embrittled, and the fabric can be torn. Also, the substitution reaction can be carried out within 5 minutes, and when it exceeds 5 minutes, an excessive reaction may occur.

The substitution reaction described above substitutes a hydroxyl group (-OH) at the terminal of the dehydrated cellulose nonwoven fabric with an anionic group such as carboxymethyl group. The above carboxymethyl group can be exemplified by-CH 2COO-Na +.

The substituted cellulose nonwoven fabric exhibits anionic water solubility, and exhibits high water replenishing property (property of protecting/maintaining moisture) and high transparency.

After the substitution reaction is completed, the cellulose nonwoven fabric derivative may be washed 2 to 3 times with water or a mixture of water and an alcohol organic solvent to remove unreacted substances. At this time, it is preferable to add an acidic chemical such as sulfuric acid, phosphoric acid, hydrochloric acid, or formic acid, acetic acid, or the like, in order to adjust the pH of the substituted cellulose nonwoven fabric, so as to neutralize the pH of the final fabric to neutrality.

< step of drying after compression (S500) >

Then, the substituted cellulose nonwoven fabric was compressed and dried to prepare a mask sheet product. The prepared mask sheet product is preferably in a non-woven form.

Specifically, after the washing, the mixture is compressed and dried at 100 to 150 ℃. When the drying temperature is less than 100 ℃, sufficient drying of the mask sheet product may not be achieved. In contrast, when the drying temperature is more than 150 ℃, yellowing may occur in the mask sheet product as the temperature increases. Also, the above-mentioned compression may be performed at 25 ± 10 ℃, and preferably, may be performed by applying pressure at 25 ± 5 ℃.

The dried mask sheet product is immersed in a solution containing a skin-improving functional ingredient having one or more of moisturizing, tranquilizing, elasticity improving, wrinkle improving, and whitening effects, and can exhibit one or more of moisturizing, tranquilizing, elasticity improving, wrinkle improving, and whitening effects.

In this way, in the present invention, by using a reaction solution in which a carboxymethylating agent is dissolved in water, and adjusting the concentration of the reaction solution, a low-substituted carboxymethyl cellulose-based sheet product having a transparency value satisfying a difference in lightness and darkness of 100 or more can be produced in a state of being immersed in water.

The mask sheet product utilizing the low-substituted carboxymethyl cellulose non-woven fabric has high transparency and can be applied as a product with excellent cost performance.

The mask sheet product prepared by the preparation method is characterized by having a thickness of 25-70 g/m²The weight of (c).

The mask sheet product prepared by the preparation method is characterized in that the carboxymethyl substitution degree is 0.05-0.3.

The mask sheet product may contain one or more skin-improving functional ingredients selected from the group consisting of moisturizing, tranquilizing, elasticity improving, wrinkle improving, and whitening, by being immersed in an essence or solution having skin-improving functionality.

Therefore, the mask sheet product of the present invention can be contacted on the skin for cosmetic purposes to provide skin-improving effects.

As described above, specific examples of the mask sheet product using the low-substituted carboxymethyl cellulose nonwoven fabric and the method for preparing the same are shown below.

The mask sheet product of the present invention is characterized in that the following formula 1 is satisfied by a transparency measurement test using a difference in brightness and darkness in a state of being immersed in water by using water and adjusting the concentration of a carboxymethylation solution.

Formula 1: d2-d1 of more than or equal to 100

Thus, the mask sheet product has characteristics of maintaining a desired form as a mask sheet product while exhibiting high transparency.

1. Preparation of mask sheet product

Example 1

Will have bidirectionality and have a density of 30g/m²The Lyocell (Lyocell) nonwoven fabric having the weight of (b) and the tensile strength and elongation described in table 1 was immersed in a 15% aqueous solution of NaOH, and then aged at 25 ℃ for 15 seconds to dissociate the hydrogen bonds of the cellulose molecules. The cured cellulose nonwoven fabric was filled to exhibit a take-up rate of 250%, and was dehydrated to be subjected to an extrusion treatment.

Then, a reaction solution in which 20 weight percent of Monochloroacetic Acid (MCA) was dissolved in 80 weight percent of distilled water was prepared in the reactor. The extruded cellulose nonwoven fabric and the reaction solution were mixed at a weight ratio of 1:5, and substitution reaction was carried out at 90 ℃ for 4 minutes.

Then, washing was performed 2 times by adding a washing solution in which ethanol and distilled water were mixed, and washing was performed 2 times by adding a washing solution containing phosphoric acid in order to adjust pH. After the washing, carboxymethyl Cellulose (CMC) nonwoven fabrics were prepared by extrusion at 25 ℃ using an automatic mangle and drying at 140 ℃.

TABLE 1

Example 2

Will have bidirectionality and have a mass fraction of 40g/m²The Lyocell (Lyocell) nonwoven fabric having the weight of (b) and the tensile strength and elongation described in table 2 was immersed in a 15% aqueous solution of NaOH, and then aged at 25 ℃ for 15 seconds to dissociate the hydrogen bonds of the cellulose molecules. The cured cellulose nonwoven fabric was filled to exhibit a take-up rate of 250%, and was dehydrated to be subjected to an extrusion treatment.

Then, a reaction solution in which 35 weight percent of Monochloroacetic Acid (MCA) was dissolved in 65 weight percent of distilled water was prepared in a reactor. The weight ratio of the extruded cellulose nonwoven fabric to the reaction solution was 1:5, and substitution reaction was carried out at 90 ℃ for 5 minutes.

Then, a cmc (carboxyymethyl cellulose) nonwoven fabric was prepared under the same conditions as in example 1.

TABLE 2

Example 3

Will have bidirectionality and have a density of 50g/m²The rayon-based nonwoven fabric having the weight of (b) and tensile strength and elongation as shown in table 3 was immersed in a 15% aqueous solution of NaOH and then aged at 25 ℃ for 15 seconds to dissociate the hydrogen bonds of the cellulose molecules. The cured cellulose nonwoven fabric was filled to exhibit a take-up rate of 250%, and was dehydrated to be subjected to an extrusion treatment.

Then, a reaction solution in which Monochloroacetic Acid (MCA) was dissolved in 70 weight percent of distilled water to 30 weight percent was prepared in a reactor. The extruded cellulose nonwoven fabric and the reaction solution were mixed at a weight ratio of 1:5, and substitution reaction was carried out at 90 ℃ for 3 minutes.

Then, a cmc (carboxyymethyl cellulose) nonwoven fabric was prepared under the same conditions as in example 1.

TABLE 3

Example 4

Will have bidirectionality and 60g/m²The rayon-based nonwoven fabric having the weight of (b) and tensile strength and elongation as shown in table 4 was immersed in a 15% aqueous solution of NaOH and then aged at 25 ℃ for 15 seconds to dissociate the hydrogen bonds of the cellulose molecules. The cured cellulose nonwoven fabric was filled to exhibit a take-up rate of 250%, and was dehydrated to be subjected to an extrusion treatment.

Then, a reaction solution in which Monochloroacetic Acid (MCA) was dissolved in 70 weight percent of distilled water to 30 weight percent was prepared in a reactor. The extruded cellulose nonwoven fabric and the reaction solution were mixed at a weight ratio of 1:5, and substitution reaction was carried out at 90 ℃ for 3 minutes.

Then, a cmc (carboxyymethyl cellulose) nonwoven fabric was prepared under the same conditions as in example 1.

TABLE 4

Comparative example 1

Prepared by DuPont (DuPont) of the United states and having a density of 26g/m²Lyocell (Lyocell) nonwoven fabrics having the weights and tensile strengths and elongations shown in table 5.

TABLE 5

Comparative example 2

Prepared by DuPont (DuPont) of the United states and having a density of 34g/m²Lyocell (Lyocell) nonwoven fabrics having the weights and tensile strengths and elongations shown in table 6.

TABLE 6

Comparative example 3

Prepared by mascot (mascot) of China having a weight of 40g/m²Tencel Skin (Tencel Skin) nonwoven fabrics having the weights of (A) and the tensile strengths and elongations shown in Table 7.

TABLE 7

Comparative example 4

Prepared by mascot (mascot) of China having a weight of 50g/m²Tencel Skin (Tencel Skin) nonwoven fabrics having the weights of (A) and the tensile strengths and elongations shown in Table 8.

TABLE 8

2. Method for evaluating physical properties and results thereof

< method for evaluating transparency >

Since there is no national standard specification for transparency of mask cloth, it is difficult to prove performance, and fig. 3 to 6 study an experimental method to perform a transparency experiment. The conventional evaluation method using transmittance is mainly an evaluation method of a material in a film form or a liquid material, and it is difficult to reflect a performance value recognized by a user of a mask product. In this experimental method, when the fiber absorbs water and has excellent transparency, the evaluation method was studied by using the measurement standard of the brightness difference of the image on the back surface of the fabric, with respect to how clearly the image on the back surface can be projected by the fabric absorbing the liquid as the measurement standard. The more excellent the transparency, the clearer the image projection on the back side of the liquid-absorbing cloth, and the greater the value of the difference in brightness of the analysis results by the image analysis program.

Fig. 3 is a view showing a transparency test apparatus for a cellulose facial film sheet excellent in transparency according to the present invention, and fig. 4 is a graph showing an analysis result by the transparency test apparatus for a cellulose facial film sheet excellent in transparency according to the present invention. As shown in the figure, in order to measure the transparency, a sample was placed on a white plate on the lower portion of which a black dot image was printed, and the sample was measured with a camera for measuring the transparency, thereby obtaining the shading values of the black dot and the white background appearing on the sample. Wherein, the obtained image is used for obtaining the brightness value of a white background and the brightness value of a black point through an image analysis program, and the difference is evaluated according to the transparency of a related sample.

Fig. 5 is an image showing a transparency test of examples 1 to 4 of the present invention, and fig. 6 is an image showing a transparency test of comparative examples 1 to 4 of the present invention. As shown in the drawing, examples 1 to 4 are characterized by satisfying the following formula 1 through the transparency measurement test of the present invention.

Formula 1: d2-d1 of more than or equal to 100

1) Evaluation of transparency

< evaluation of transparency >

a. Samples to be evaluated for transparency were prepared in a size of 10X 10 cm.

b. The prepared sample was allowed to completely absorb distilled water 3 times the weight of the sample and left to stand for 5 minutes.

c. A liquid-absorbing sample was placed on a white plate printed with an image of a black dot.

d. After an image projected together with the sample absorbing the liquid was captured by the imaging device, the values of D1 (light and dark floor) and D2 (light and dark background) were obtained by an image analysis program.

e. The transparency value was obtained by the following formula (formula 1), and the higher the transparency value, the better the transparency was evaluated.

Formula 1: transparency D2-D1

D1: bright and dark bottom plate (Black dot)

D2: background brightness (white background)

Table 9 shows the transparency values based on the difference in brightness in the state where the mask nonwoven fabrics before and after the reaction according to examples 1 to 4 were immersed in water.

TABLE 9

Based on the above experimental results, the nonwoven fabrics for face masks according to examples 1 to 4 exhibited an average value of 100 or more after transparency reaction.

On the other hand, table 10 shows transparency values based on differences in brightness in a state where the nonwoven fabrics for a mask pack according to comparative examples 1 to 4 were immersed in water.

Watch 10

Remarks for note	D2	D1	Transparency (poor brightness)
				Comparative example 1	182.1	88.6	93.5
Comparative example 2	161.8	72.3	89.5
				Comparative example 3	143.2	53.9	89.3
Comparative example 4	146.7	60.5	86.2

From the above experimental results, it was confirmed that the transparency was poor because the raw paper before the reaction and comparative examples 1 to 4 could not satisfy the range of transparency value proposed in the present invention.

Evaluation of physical Properties

Table 11 shows the tensile strength and elongation in the md (machine direction) direction and cd (cross direction) direction of the nonwoven fabrics for face mask before and after the reaction according to examples 1 to 4, and table 12 shows the weight and thickness of the nonwoven fabrics for face mask before and after the reaction according to examples 1 to 4.

TABLE 11

TABLE 12

As shown in table 11, it is understood that the tensile strength and elongation in the md (machine direction) direction and the cd (cross direction) direction of the nonwoven fabrics for a face mask before reaction according to examples 1 to 4 were reduced after the reaction, and the increase in transparency was not determined due to the thinned fabric after the reaction, and thus the weight and thickness before and after the reaction were measured.

As a result, as shown in table 12, it was found that the nonwoven fabrics for a face mask according to examples 1 to 4 exhibited similar values of weight and thickness measured before and after the reaction, and the transparency did not increase with decrease in weight and thickness.

Although the embodiments of the present invention have been described above mainly, various modifications and changes can be made by those skilled in the art to which the present invention pertains. Such changes and modifications are to be considered as included in the present invention unless they depart from the scope of the technical ideas provided by the present invention. Accordingly, the scope of the invention should be determined from the following claims.

The invention thus constituted has the following advantages: the mask sheet of the present invention can greatly improve the use satisfaction when attached to the face by greatly improving the transparency.

Although the preferred embodiments for illustrating the principles of the present invention have been described and illustrated, the present invention is not limited to the structures and operations illustrated and described. On the contrary, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the appended claims. Accordingly, it is intended that all such suitable variations and modifications and equivalents be considered as within the scope of the present invention.