A flexible release film with a low release force and its preparation method

Abstract

The present invention provides a flexible release film with a low release force and a preparation method thereof. The method includes the following steps: preparing a polyaspartic acid-modified chitosan solution as electrospinning solution A; preparing a PVA solution and adding "sponge-like" aerogel particles to serve as electrospinning solution B; using electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution to perform coaxial electrospinning to obtain a flexible release film with a low release force. For the hydrogel release film prepared from the composite fibers with a "core-shell" structure in the present invention, when the hydrogel release film is subjected to external force impact, the modified chitosan layer with a rigid network dissipates energy, and the PVA layer with a flexible network structure maintains the integrity of the hydrogel release film, thereby achieving good mechanical properties. The "sponge-like" aerogel particles generate protrusions on the surface of the hydrogel film, infiltrate air, thereby reducing the negative pressure between the films, reducing the release force, achieving the effect of a low release force, and enabling rapid separation.

Description

Technical Field

[0001] The present invention relates to the technical field of release films, and particularly to a flexible release film with a low release force and a preparation method thereof. Background Art

[0002] Release films, also known as isolation films, peeling films, separation films, etc. The most commonly used one at present is the PET release film, which is to perform surface treatment on a PET substrate, including coating a silicone release agent, a fluorine-based release agent, or performing plasma treatment, so that it has an extremely low and stable release force for different organic pressure-sensitive adhesives. This is the most common release film product. With the same substrate and different release agents, the release forces of the produced release films are also different. From the perspective of the release force, it can be divided into low-release-force release films, medium-release-force release films, and high-release-force release films; in terms of structure, it can be divided into adhesive release films, composite release films, laser films, and non-adhesive release films; in terms of function, it can be divided into isolation release films, protection release films, waterproof release films, light diffusion release films, printing release films, and tape release films. However, the PET release film has a relatively hard material and cannot be used in many scenarios. The hydrogel film has great flexibility and can make up for its application. However, the hydrogel film also has the disadvantage of poor mechanical properties. Therefore, by modifying the hydrogel film and designing its structure, it is also of great market value to prepare a flexible release film with good mechanical properties and a low release effect. Summary of the Invention

[0003] Technical problems to be solved: Aiming at the above technical problems, the purpose of the present invention is to provide a flexible release film with a low release force and a preparation method thereof. The hydrogel release film is prepared by using the coaxial electrospinning method to obtain composite fibers with a "core-shell" structure. The core layer of the composite fiber is a modified chitosan layer with a rigid network, and the shell layer is a PVA layer with a flexible network structure. When the hydrogel release film is subjected to external force impact, the modified chitosan layer with a rigid network dissipates energy, and the PVA layer with a flexible network structure maintains the integrity of the hydrogel release film, so as to achieve good mechanical properties. By generating protrusions on the surface of the hydrogel film with "sponge-like" aerogel particles and infiltrating air, the negative pressure between the films is reduced, the release force is reduced, and the effect of a low release force is achieved, enabling rapid separation.

[0004] Technical solution: A preparation method of a flexible release film with a low release force, calculated by weight, includes the following steps:

[0005] S1: Dissolve chitosan in a 2% aqueous solution of glacial acetic acid, and fully dissolve it in a water bath at 30°C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution and stir well to obtain a modified chitosan solution, which is used as electrospinning solution A;

[0006] S2: Take 2 portions of PVA and place them in a dry small beaker. Add 20 portions of water and dissolve them in a water bath at 95 °C. Then add "sponge-like" aerogel particles to obtain electrospinning solution B.

[0007] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution. Inject them into two syringes in a coaxial electrospinning device respectively and conduct coaxial electrospinning to obtain a flexible release film with low release force.

[0008] Further, the volume ratio of the chitosan solution to the polyaspartic acid solution is (2 - 3):1.

[0009] Further, the particle size of the "sponge-like" aerogel particles ≤ 0.1 μm.

[0010] Further, the mass ratio of PVA to the "sponge-like" aerogel particles is 10:(0.2 - 0.6).

[0011] Further, the preparation method of the "sponge-like" aerogel particles is as follows:

[0012] S21: Take a three-dimensional network polyvinyl alcohol skeleton and immerse it in a metal oxide sol for 1 - 2 h;

[0013] S22: Take it out, place it in an ethanol atmosphere to gel and age to obtain a composite of the three-dimensional network polyvinyl alcohol skeleton and the metal oxide sol;

[0014] S23: Dry the composite to obtain a "sponge-like" aerogel;

[0015] S24: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles.

[0016] Further, the coaxial electrospinning conditions are: the core layer flow rate is (0.5 - 1.0) mL / h, the shell layer flow rate is 0.6 mL / h, the electrospinning voltage is 20 kV, the environmental temperature is 30 - 45 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm.

[0017] Further, the mass ratio of the three-dimensional network polyvinyl alcohol skeleton to the metal oxide sol is (1 - 3):10.

[0018] Further, the preparation method of the metal oxide sol is: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2.

[0019] Further, the aging temperature is 40 - 50 °C and the aging time is 5 - 10 h. Beneficial effects

[0020] The hydrogel release film prepared by the present invention using coaxial electrospinning to obtain composite fibers with a "core-shell" structure, where the core layer of the composite fiber is a modified chitosan layer with a rigid network, and the shell layer is a PVA layer with a flexible network structure. When the hydrogel release film is subjected to external impact, the modified chitosan layer with a rigid network dissipates energy, and the PVA layer with a flexible network structure maintains the integrity of the hydrogel release film, thus achieving good mechanical properties.

[0021] In the present invention, "sponge-like" aerogel particles are added to the PVA layer. On the one hand, the "sponge-like" aerogel particles can further absorb external forces, reduce damage to the hydrogel film, and improve mechanical properties. On the other hand, they can produce protrusions on the surface of the hydrogel film, infiltrate air, thereby reducing the negative pressure between the films, reducing the release force, achieving the effect of a light release force, and enabling rapid separation.

[0022] In the present invention, chitosan is modified with polyaspartic acid. Polyaspartic acid contains a large number of carboxyl groups and an appropriate amount of amino structures, which can be cross-linked with each other. At the same time, by binding to chitosan, it can change its strong internal and intermolecular hydrogen bonds and improve its mechanical properties.

[0023] The chitosan modified with polyaspartic acid in the present invention also has a scale inhibition effect, which can keep the hydrogel film clean during application.

[0024] The hydrogel release film of the present invention has the characteristic of "flexibility", can be bent and folded arbitrarily, is suitable for various types of scenarios, and expands the application range of ordinary release films. Detailed implementation manners

[0025] The present invention provides a flexible release film with a light release force and its preparation method. To make the purpose, technical solution and effect of the present invention clearer and more definite, the following will further elaborate on the present invention in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0026] The preparation method of the "sponge-like" aerogel particles is as follows:

[0027] S21: The preparation method of the metal oxide sol is: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate: ethanol: water: acetic acid is 1:8:4:2;

[0028] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:10;

[0029] S23: Take it out, place it in an ethanol atmosphere to gel and age. The aging temperature is 45°C and the aging time is 8 h to obtain a composite of a three-dimensional network polyvinyl alcohol skeleton and a metal oxide sol;

[0030] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0031] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 2

[0032] The preparation method of the "sponge-like" aerogel particles is as follows:

[0033] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0034] S22: Take a three-dimensional network polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional network polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0035] S23: Take it out, place it in an ethanol atmosphere to gel and age. The aging temperature is 45°C and the aging time is 8 h to obtain a composite of a three-dimensional network polyvinyl alcohol skeleton and a metal oxide sol;

[0036] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0037] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 3

[0038] The preparation method of the "sponge-like" aerogel particles is as follows:

[0039] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0040] S22: Take a three-dimensional network polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional network polyvinyl alcohol skeleton to the metal oxide sol is 3:10;

[0041] S23: Take it out, place it in an ethanol atmosphere to gel and age. The aging temperature is 45°C and the aging time is 8 h to obtain a composite of a three-dimensional network polyvinyl alcohol skeleton and a metal oxide sol;

[0042] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0043] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 4

[0044] The preparation method of the "sponge-like" aerogel particles is as follows:

[0045] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0046] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0047] S23: Take it out, place it in an ethanol atmosphere for gelation and aging, the aging temperature is 45 °C, and the aging time is 8 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0048] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0049] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 5

[0050] The preparation method of the "sponge-like" aerogel particles is as follows:

[0051] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0052] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 2 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0053] S23: Take it out, place it in an ethanol atmosphere for gelation and aging, the aging temperature is 45 °C, and the aging time is 8 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0054] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0055] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 6

[0056] The preparation method of the "sponge-like" aerogel particles is as follows:

[0057] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0058] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0059] S23: Take it out, place it in an ethanol atmosphere to gel and age, the aging temperature is 40 °C, and the aging time is 8 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0060] S24: Dry the composite to obtain the "sponge-like" aerogel;

[0061] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 7

[0062] The preparation method of the "sponge-like" aerogel particles is as follows:

[0063] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0064] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0065] S23: Take it out, place it in an ethanol atmosphere to gel and age, the aging temperature is 50 °C, and the aging time is 8 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0066] S24: Dry the composite to obtain the "sponge-like" aerogel;

[0067] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 8

[0068] The preparation method of the "sponge-like" aerogel particles is as follows:

[0069] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0070] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0071] S23: Take it out, place it in an ethanol atmosphere to gel and age, the aging temperature is 45 °C, and the aging time is 5 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0072] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0073] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm. Example 9

[0074] The preparation method of the "sponge-like" aerogel particles is as follows:

[0075] S21: The preparation method of the metal oxide sol is as follows: Mix tetrabutyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of tetrabutyl titanate:ethanol:water:acetic acid is 1:8:4:2;

[0076] S22: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in the metal oxide sol for 1.5 h; the mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol is 1:5;

[0077] S23: Take it out, place it in an ethanol atmosphere to gel and age, the aging temperature is 45 °C, and the aging time is 10 h to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol;

[0078] S24: Dry the composite to obtain a "sponge-like" aerogel;

[0079] S25: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles with a particle size ≤ 0.1 μm.

[0080] Measure the porosity, pore size and mechanical properties of the "sponge-like" aerogel particles.

[0081] Table 1

[0082]

[0083] After comparison, the "sponge-like" aerogel particles prepared in Example 1, Example 4, and Example 7 were selected for subsequent tests.

[0084] Example 10

[0085] A method for preparing a flexible release film with a low release force, in parts by weight, includes the following steps:

[0086] S1: Dissolve chitosan in a 2% aqueous acetic acid solution, and fully dissolve it in a water bath at 30°C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2:1 and stir well to obtain a modified chitosan solution as electrospinning solution A.

[0087] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95°C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4.

[0088] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are: the core layer flow rate is 0.8 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40°C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0089] Example 11

[0090] A method for preparing a flexible release film with a low release force, in parts by weight, includes the following steps:

[0091] S1: Dissolve chitosan in a 2% aqueous acetic acid solution, and fully dissolve it in a water bath at 30°C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 3:1 and stir well to obtain a modified chitosan solution as electrospinning solution A.

[0092] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95°C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4.

[0093] S3: Use electrospinning solution A as the core layer electrospinning solution and electrospinning solution B as the shell layer electrospinning solution. Inject them into two syringes in a coaxial electrospinning device respectively and conduct coaxial electrospinning. The coaxial electrospinning conditions are as follows: the flow rate of the core layer is 0.8 mL / h, the flow rate of the shell layer is 0.6 mL / h, the electrospinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm, to obtain a flexible release film with a light release force.

[0094] Example 12

[0095] A preparation method of a flexible release film with a light release force, by weight, includes the following steps:

[0096] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution, as electrospinning solution A;

[0097] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4;

[0098] S3: Use electrospinning solution A as the core layer electrospinning solution and electrospinning solution B as the shell layer electrospinning solution. Inject them into two syringes in a coaxial electrospinning device respectively and conduct coaxial electrospinning. The coaxial electrospinning conditions are as follows: the flow rate of the core layer is 0.8 mL / h, the flow rate of the shell layer is 0.6 mL / h, the electrospinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm, to obtain a flexible release film with a light release force.

[0099] Example 13

[0100] A preparation method of a flexible release film with a light release force, by weight, includes the following steps:

[0101] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution, as electrospinning solution A;

[0102] S2: Take 2 parts of PVA and place it in a dry small beaker. Add 20 parts of water and dissolve it in a water bath at 95 °C. Then add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 to obtain electrospinning solution B. Among them, the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.2;

[0103] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution. Inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are as follows: the core layer flow rate is 0.8 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0104] Example 14

[0105] A method for preparing a flexible release film with a low release force, in parts by weight, includes the following steps:

[0106] S1: Dissolve chitosan in a 2% aqueous solution of glacial acetic acid and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution as electrospinning solution A;

[0107] S2: Take 2 parts of PVA and place it in a dry small beaker. Add 20 parts of water and dissolve it in a water bath at 95 °C. Then add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 to obtain electrospinning solution B. Among them, the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.6;

[0108] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution. Inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are as follows: the core layer flow rate is 0.8 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0109] Example 15

[0110] A method for preparing a flexible release film with a low release force, in parts by weight, includes the following steps:

[0111] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution, which is used as electrospinning solution A;

[0112] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4;

[0113] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are: the core layer flow rate is 0.5 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0114] Example 16

[0115] A method for preparing a flexible release film with a low release force, in parts by weight, includes the following steps:

[0116] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution, which is used as electrospinning solution A;

[0117] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4;

[0118] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are: the core layer flow rate is 1.0 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0119] Example 17

[0120] A preparation method of a flexible release film with a low release force, in parts by weight, includes the following steps:

[0121] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution as electrospinning solution A;

[0122] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 1 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4;

[0123] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into 2 syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are: the core layer flow rate is 0.8 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film with a low release force.

[0124] Example 18

[0125] A preparation method of a flexible release film with a low release force, in parts by weight, includes the following steps:

[0126] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution as electrospinning solution A;

[0127] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 4 as electrospinning solution B, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4;

[0128] S3: Use electrospinning solution A as the core layer electrospinning solution and electrospinning solution B as the shell layer electrospinning solution. Inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are as follows: the flow rate of the core layer is 0.8 mL / h, the flow rate of the shell layer is 0.6 mL / h, the electrospinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm, to obtain a flexible release film with a low release force.

[0129] Comparative Example 1

[0130] The difference between this example and Example 12 is that the "core-shell" structure is not adopted. Specifically:

[0131] A method for preparing a flexible release film, in parts by weight, includes the following steps:

[0132] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution.

[0133] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add the "sponge-like" aerogel particles with a particle size ≤ 0.1 μm prepared in Example 7 to obtain a PVA solution, where the mass ratio of PVA to the "sponge-like" aerogel particles is 10:0.4.

[0134] S3: Mix and stir the modified chitosan solution and the PVA solution evenly as the electrospinning solution, inject it into the syringe in the electrospinning device, and perform electrospinning. The electrospinning conditions are as follows: the flow rate of the electrospinning solution is 0.6 mL / h, the electrospinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm, to obtain a flexible release film.

[0135] Comparative Example 2

[0136] The difference between this example and Example 12 is that the "sponge-like" aerogel particles are replaced with SiO2 particles with an elastic modulus of 0.65 and a particle size ≤ 0.1 μm. Specifically:

[0137] A method for preparing a flexible release film, in parts by weight, includes the following steps:

[0138] S1: Dissolve chitosan in a 2% aqueous acetic acid solution and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution with a volume ratio of 2.5:1 and stir well to obtain a modified chitosan solution, which is used as electrospinning solution A.

[0139] S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add SiO2 particles to obtain electrospinning solution B, where the mass ratio of PVA to SiO2 particles is 10:0.4.

[0140] S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning. The coaxial electrospinning conditions are: the core layer flow rate is 0.8 mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 40 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm to obtain a flexible release film.

[0141] The release film prepared in the above example has a thickness of 28 μm, which is cut into strips of 1 cm × 4 cm, and its mechanical properties are measured by a universal tensile machine with a loading speed of 2 mm / min and a tensile speed of 5 mm / min.

[0142] Test the release force of the release film through ASTM D3330 / D3330M-04 (2018), and the results are shown in Table 2:

[0143] Table 2

[0144]

[0145] It can be seen from Table 2 that the mass ratio of the chitosan solution and the polyaspartic acid solution has a greater impact on the compressive strength, and the "sponge-like" aerogel particles also have a greater impact on the compressive strength. This is mainly because the "sponge-like" aerogel particles can further absorb external forces through their own compression, reduce the damage to the hydrogel film, and improve the compressive strength; while the core layer flow rate has a smaller impact on the mechanical properties of the release film. At the same time, the release force of this application is also very low, with a minimum of 1.4 cN / 2.5 cm, which fully meets the requirements of a light release force.

Claims

1. A preparation method of a flexible release film with a low release force, characterized in that, Comprising the following steps by weight parts: S1: Dissolve chitosan in a 2% aqueous acetic acid solution, and fully dissolve it in a water bath at 30 °C to obtain a 3.5 wt.% chitosan solution; fully dissolve polyaspartic acid in water to obtain a 3 wt.% polyaspartic acid solution; mix the chitosan solution and the polyaspartic acid solution and stir well to obtain a modified chitosan solution as electrospinning solution A. S2: Take 2 parts of PVA and put it into a dry small beaker, add 20 parts of water, dissolve it in a water bath at 95 °C, and add "sponge-like" aerogel particles to obtain electrospinning solution B. S3: Use electrospinning solution A as the core layer spinning solution and electrospinning solution B as the shell layer spinning solution, and inject them into two syringes in a coaxial electrospinning device respectively for coaxial electrospinning to obtain a flexible release film with a low release force. The preparation method of the "sponge-like" aerogel particles is as follows: S21: Take a three-dimensional reticulated polyvinyl alcohol skeleton and immerse it in a metal oxide sol for 1 - 2 h. S22: Take it out, place it in an ethanol atmosphere to gel and age to obtain a composite of the three-dimensional reticulated polyvinyl alcohol skeleton and the metal oxide sol. S23: Dry the composite to obtain a "sponge-like" aerogel. S24: Crush the "sponge-like" aerogel to obtain "sponge-like" aerogel particles.

2. The preparation method of a flexible release film with a low release force according to claim 1, characterized in that, The volume ratio of the chitosan solution to the polyaspartic acid solution is (2 - 3):

1.

3. The preparation method of a flexible release film with a low release force according to claim 1, wherein, The particle size of the "sponge-like" aerogel particles ≤ 0.1 μm.

4. The preparation method of a flexible release film with a low release force according to claim 1, characterized in that, The mass ratio of the PVA to the "sponge-like" aerogel particles is 10:(0.2 - 0.6).

5. The preparation method of a flexible release film with a low release force according to claim 1, characterized in that, The coaxial electrospinning conditions are: the core layer flow rate is (0.5 - 1.0) mL / h, the shell layer flow rate is 0.6 mL / h, the spinning voltage is 20 kV, the ambient temperature is 30 - 45 °C, the humidity is 40%, and the distance from the receiving plate is 15 cm.

6. The preparation method of a flexible release film with a low release force according to claim 1, characterized in that, The mass ratio of the three-dimensional reticulated polyvinyl alcohol skeleton to the metal oxide sol in S21 is: (1 - 3):

10.

7. The preparation method of a flexible release film with a low release force according to claim 1, wherein, The preparation method of the metal oxide sol in S21 is: Mix butyl titanate with ethanol and water evenly, then add acetic acid and stir to obtain the metal oxide sol; the molar ratio of butyl titanate:ethanol:water:acetic acid is 1:8:4:

2.

8. The preparation method of a flexible release film with a low release force according to claim 1, wherein, The aging temperature in S22 is 40 - 50 °C, and the aging time is 5 - 10 h.

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