TWI673407B - Biofiber dry mask and drying method thereof - Google Patents

Abstract

A method for drying a biofiber dry mask includes: step one, an acid ion removal step; step two, a film thickness control step; step three, a mask forming step; and step four, a radio frequency drying step. The bio-fiber dry mask made by the above method has physical properties such as a moisture content of 6-10%, a tensile strength of about 5.3-5.4MPa, a browning rate change rate of less than 8%, and a water rehydration rate of 25-30%. feature.

Description

Biological fiber dry mask and drying method thereof

The invention relates to a drying technology of a biological fiber mask.

The bio-fiber mask has a moisture content of more than 80-90%, and the moisture content is much higher than that of non-woven fabrics, cotton cloths, etc. Therefore, the bio-fiber mask has high biocompatibility and a higher degree of fit to the skin than other material masks. However, the high moisture content of the biofiber mask itself has also led to the problem of easy breeding of bacteria. In addition, when biofiber masks are used with viscous essences such as hyaluronic acid and polysaccharide solutions, the high moisture content of the mask itself makes it difficult to carry this type of essence, and the concentration of the essence in each mask is difficult to control to achieve expectations.

Hot air drying is one of the current processing techniques for processing bio-fiber masks. Hot air is mainly used to condense and conduct heat to the inside of objects. In the first stage of hot air drying, free water diffuses to the surface of the mask and is evaporated and removed. In the second stage, because the surface of the mask absorbs thermal energy, it causes tissue degeneration, even browning or tissue hardening, which seriously affects the product quality of the mask. As a result, the bio-fiber mask is less likely to carry essence.

An object of the present invention is to provide a method for drying a bio-fiber mask.

The technical feature of the present invention is a method for drying a bio-fiber dry mask, which includes the following steps: a step of removing acid ions, reducing the pH of a bio-fiber preliminary film to 6.7-7.2; Step 2: The film thickness control step excludes the free water of the biofiber preliminary film, and reduces the film thickness to 0.30-0.35cm; Step three, the mask forming step, cuts the biofiber preliminary film into one by cutting and punching. Mask shape; step four, RF drying step, put the mask in a vacuum RF drying system to dry it to a dry mask with a moisture content of 6-10%; the operating condition of the vacuum RF drying system is temperature: 30-60 ℃, power: 3-5W, frequency: 30-40MHz, the distance between the RF laminates is 13-17cm. Time required for drying: 38-42 seconds.

The best operating conditions for RF drying are a temperature of 40 ° C, a power of 5W, a frequency of 40MHz, and a radio frequency board spacing of 15cm. The time required for drying is 40 seconds.

A biofiber dry mask made by the above method, characterized in that the dry mask has a moisture content of 6-10%, a tensile strength of about 5.3-5.4MPa, a browning rate change rate of less than 8%, and rehydration. The rate reaches 25-30%.

Efficacy of the present invention: The dry mask dried by the method of the present invention can inhibit the increase of microorganisms with low moisture content, low change rate of browning degree of the mask, no brown spots, high tensile strength, and high rehydration rate. Sex.

The optimal conditions for RF drying set above were compared with 60 ° C hot air drying. It can be known from the results that at the same temperature and processing time, the drying rate of RF drying is better than that of hot air drying. Reduce the moisture content of the mask to 8% faster to maintain the structural integrity of the fiber.

1‧‧‧ lower plate

2‧‧‧Mask

3‧‧‧ Upper board

5‧‧‧ RF System

D‧‧‧Pitch

The first graph is a bar graph of the tensile strength of the dry mask with moisture content of 6%, 8%, and 10%.

The second figure is a bar graph of tensile strength of the dry mask after RF drying and hot air drying.

The third figure is a bar chart of the rehydration rate of the dry mask after RF drying and hot air drying.

The fourth figure is a line chart of the hyaluronic acid adsorption rate of the dry mask with a moisture content of 2%, 5%, 8%, 11%, and 14% after RF drying.

The fifth figure is a bar chart of the time required for drying the squeezed and unpressed mask by RF drying to achieve a moisture content of 8%.

The sixth figure is a bar chart of the time required for the masks with a thickness of 0.30cm, 0.35cm, and 0.40cm to be dried by RF drying so that the moisture content reaches 8%.

The seventh figure is a bar chart of the browning rate of the dry mask caused by RF drying temperatures of 30 ° C, 60 ° C, and 90 ° C.

The eighth figure is a bar chart of the browning rate of the dry mask caused by the RF power of 3W, 5W, 7W, and 10W.

The ninth figure is a bar chart of the browning rate of the dry mask caused by RF frequencies of 30 MHz, 40 MHz, and 50 MHz.

The tenth figure is a bar chart of the time required for the dry mask to reach a moisture content of 8% with RF frequencies of 30MHz, 40MHz, and 50MHz.

The eleventh figure is a bar chart of the time required for the dryness of the dry mask to reach a moisture content of 8% when the spacing between the layers of the radio frequency system is 10 cm, 15 cm, and 20 cm.

The twelfth figure is a schematic diagram of the board spacing of the RF system.

The thirteenth figure is a line chart of the drying rate of the RF mask and hot air drying with the target moisture content of 8%.

The drying method of the biological fiber mask of the present invention comprises:

Step one, an acid ion removing step. Bleaching the primary membrane of biological fiber with deionized water Wash to reduce the pH value of the primary membrane of the biofiber to 6.7-7.2. Because the primary membrane of the biological fiber is subjected to the fermentation process of acetic acid bacteria during the production process, it has a high concentration of acidic ions, and the high concentration of acidic ions consumes the dielectric heating energy, which will prolong the operation time of the subsequent RF drying step. Acidic ions are removed from the primary membrane of the biofiber. The removal of acidic ions is represented by the pH value of the primary membrane of the biological fiber. When the pH value is neutral, it means that the acidic ions have been largely removed.

Step two, the film thickness control step. The biofiber primary membrane is extruded with a press, the free water contained in the biofiber primary membrane is excluded, and the film thickness is compressed to 0.30-0.35cm.

Step three, the mask forming step. Through the cutting and punching technology, according to the shape of the existing mask, the biofiber primary film is cut and punched into a biofiber mask.

Step 4: RF drying step. The bio-fiber mask is dried in a vacuum radio frequency drying system, so that the moisture content is reduced to 6-10% (the best is 8%); the operating conditions of the vacuum radio frequency drying system are: 30-60 ° C (best 40 ° C), power: 3-5W (best is 5W), frequency: 30-40MHz (best is 40MHz), radio frequency board spacing is 13-17cm (best is 15cm). Drying time: 38-42 seconds (optimally 40 seconds)

The importance and necessity of maintaining the moisture content of the dry mask at 6-10% (optimally 8%) are illustrated by the experimental data in the first to fourth graphs.

As shown in the first figure, three dry mask samples were tested for tensile strength. The moisture content of the three dry masks was 6%, 8%, and 10%, respectively. The tensile strength of a dry mask with a moisture content of 6% is about 4.5-4.6MPa, the tensile strength of a dry mask with a moisture content of 8% is about 5.3-5.4MPa, and the tensile strength of a dry mask with a moisture content of 10% is about 4.8-5MPa. This experimental data shows that a dry mask with a moisture content of 8% exhibits better tensile strength.

As shown in the second figure, the dry mask of the present invention and the dry mask dried by hot air are stretched. In comparison, the tensile strength of the dry mask dried by hot air is 4 MPa, and the tensile strength of the dry mask of 8% moisture content of the present invention is 5.3-5.4 MPa, which is higher than the dry mask dried by hot air. Not only that, the dry facial masks of the three moisture content of the present invention all have higher tensile strength than the dry facial masks dried by hot air. The dry mask with high tensile strength can withstand mechanical pressure such as folding, sucking essence, bagging, etc., and is not easy to rupture, and it is less likely to rupture when unfolded, and it can be applied to the user's face to fit the skin.

As shown in the third figure, the dry mask of the present invention with a moisture content of 6% -10% is also superior to the traditional hot air-dried dry mask in the performance of rehydration. Rehydration rate (%) = [(wet weight after rewatering-dry weight after drying) / (wet weight of original sample-dry weight after drying)] × 100%. A higher rehydration rate means that the dry mask has better carrying capacity of the essence. According to the present invention, the rehydration rate of the dry mask with a moisture content of 6% -10% is 26% -27%, and the rehydration rate of the dry mask dried by hot air is 16% -19%.

As shown in the fourth figure, the moisture content of the object is higher than 13%, which is easy to cause mold growth, and the mask product is a high-moisture object and is in contact with human skin. Therefore, it is necessary to suppress the microorganisms on the mask to increase the safety factor. Poor solution, it may cause unexpected problems of human skin, so the present invention reduces the moisture content to improve the bacteriostatic properties of the dry mask. However, the ability to suck the essence should be considered while reducing the moisture content of the dry mask. The moisture content of the dry mask can also be reduced to 2%, but the content of the essence (hyaluronic acid) of the mask is not significantly higher than that of the mask with a moisture content of 6% -10%, and the moisture content of the mask is reduced to 2%. Prolonging the RF drying time may cause problems such as browning, wrinkling, or reduction in tensile strength of the dry mask. Therefore, the moisture content of 6% -10% is the preferred range of moisture content of the dry mask of the present invention, and the most preferred is 8%.

The importance and necessity of the film thickness control step in the second step of the present invention are illustrated by the experimental data of the fifth graph to the sixth graph. The film thickness control step actually includes two parts, one is to remove the free water of the initial film by the press, and the other is to compress the free film thickness to 0.30-0.35cm.

As shown in the fifth figure, the pressed and unpressed primary film has a temperature of 40 ° C, a power of 5W, a frequency of 40MHz, a radio frequency board spacing of 15cm, and a drying time of 40 seconds for radio frequency drying and a dry mask moisture content of 8%. The RF drying time of the primary film after the pressing step is 40-41 seconds, and the RF drying time of the primary film without the pressing step is 65-68 seconds. It is shown that the pressed primary film can greatly shorten the RF drying time.

As shown in the sixth figure, the effect of initial film thickness on RF drying. The three primary film samples were dried at a temperature of 40 ° C, a power of 5W, a frequency of 40MHz, a radio frequency board spacing of 15cm, a drying time of 40 seconds, and a moisture content of 8% for the dry mask. The thicknesses of the three primary films are 0.3 cm, 0.35 cm, and 0.4 cm, respectively. The RF drying time is 39-41 seconds, 37-38 seconds, and 45-47 seconds. Experimental data show that controlling the film thickness to 0.30-0.35cm can shorten the time required for RF drying.

The effect of the operation conditions of the fourth step of the radio frequency drying of the present invention on the color of the bio-fiber mask is to achieve a moisture content of 8% of the dry mask as the goal, and the experimental data of FIGS. 7 to 11 are used to illustrate the results.

The seventh picture, the power is 5W, the frequency is 40MHz, the RF laminate spacing is 15cm, the drying time is 40 seconds, and the temperature is 30 ° C, 60 ° C, and 90 ° C. The influence of the power on the browning degree of the dry mask. The eighth figure, the temperature is 40 ° C, the frequency is 40MHz, the interval between the RF laminates is 15cm, the drying time is 40 seconds, and the power is 3W, 5W, 7W, 10W, which affects the degree of browning. The ninth figure, the temperature is 40 ° C, the power is 5W, the interval between the RF laminates is 15cm, the drying time is 40 seconds, and the RF frequencies 30MHz, 40MHz, and 50MHz affect the browning degree. The experimental data on the opening shows that the temperature as high as 90 ° C, the power as high as 10W, and the frequency as high as 50MHz will make the dry mask produce a significant degree of browning. Based on this, the vacuum RF drying system is relatively The best operating conditions are temperature: 30-60 ° C (best is 40 ° C), power: 3-5W (best is 5W), frequency: 30-40MHz (best is 40MHz), time: 38-42 seconds (best (It is preferably 40 seconds), which can reduce the change rate of browning degree to less than 8%, and the dry mask has no brown spots.

As shown in the tenth figure, the effect of RF frequency on RF drying time is based on the temperature of 40 ° C, power of 5W, the distance between RF laminates is 15cm, and the moisture content of the dry mask is 8%. The drying time at 30MHz is about 52-53. Seconds, RF frequency 40MHz drying time is about 41-42 seconds seconds, RF frequency 50MHz drying time is about 47-49 seconds. Shows that the RF frequency is 40MHz to achieve the shortest drying time.

The eleventh figure shows the impact of the RF system layer spacing on the RF dried biofiber mask. Aiming at a temperature of 40 ° C, a power of 5W, and a frequency of 40MHz, to achieve a dry mask moisture content of 8%, the drying time required for a layer distance of 10cm is 42-44 seconds, and the drying time required for a layer distance of 15cm is 39-40 seconds. The drying time required for a plate spacing of 20 cm is 47-48 seconds. The shortest drying time can be achieved with a display layer spacing of 15cm. Please refer to the twelfth figure for the distance between the five layers of the RF system. The layer 1 is a radio frequency power electrode plate. A mask 2 is placed on the power electrode plate. The distance D between the upper layer 3 and the lower layer 1 is the layer. spacing.

As shown in the thirteenth figure, the optimal RF drying conditions set earlier are compared with 60 ° C hot air drying. It can be known from the results that at the same temperature and processing time, the drying rate of RF drying is better than that of hot air drying. Reduce the moisture content of the mask to 8% faster to maintain the structural integrity of the fiber.

Claims (6)

A method for drying a biofiber dry mask, comprising: step one, removing acidic ions, reducing the pH value of a biofiber primary film to 6.7-7.2; step two, a film thickness control step, excluding the biofiber primary film. Free water, and reduce the film thickness to 0.30-0.35cm; Step three, the mask forming step, cutting the biofiber preliminary film into a mask shape by cutting and punching; step four, the RF drying step, placing the mask on Dry in a vacuum radio frequency drying system to dry it into a dry mask with a moisture content of 6-10%; the operating conditions of the vacuum radio frequency drying system are temperature: 30-60 ° C, power: 3-5W, frequency: 30-40MHz, The interval of the RF laminate is 13-17cm, and the time required for drying: 38-42 seconds. The method for drying a biofiber dry mask according to claim 1, wherein in step one, the biofiber primary film is rinsed with deionized water. The method for drying a biofiber dry mask according to claim 1, wherein the second step is to press the biofiber primary film with a press. The method for drying a biofiber dry mask according to claim 1, wherein the moisture content of the dry mask is 8%. The drying method of the biofiber dry mask according to claim 1 or 4, wherein in the fourth step, the temperature is 40 ° C, the power is 5W, the frequency is 40MHz, the interval between the radio frequency laminates is 15cm, and the drying time is 40 seconds. A biofiber dry mask made according to the method of claim 1, characterized in that the dry mask has a moisture content of 6-10%, a tensile strength of about 5.3-5.4MPa, and a browning degree change rate of less than 8%, And the rehydration rate reaches 25-30%.