Preparation method of photocuring release agent suitable for flexible substrate

Abstract

The invention discloses a preparation method of a photocuring release agent suitable for a flexible substrate, and belongs to the technical field of release agents. The preparation method disclosed by the invention comprises the following steps: respectively preparing the dynamic epoxy acrylate, the biological fiber and the SiO2 (at) PDMS compound; the preparation method comprises the following steps: adding dynamic epoxy acrylate, a flexible monomer PEG400DA and an antistatic agent into a reaction kettle, stirring in a water bath at 60 DEG C, adding biological fibers and the SiO2-coated PDMS compound, dispersing, grinding by three rollers, adding a photoinitiator, a flatting agent and a defoaming agent, stirring at a low speed under a dark condition, and transferring a mixed solution to a vacuum defoaming machine for treatment. Through dynamic covalent bond design, a synergistic effect of a biological-inorganic composite material and refined process control, the problems of high shrinkage, low flexibility and insufficient interface bonding force of a flexible substrate photocuring release agent are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of release agents, and particularly relates to a preparation method of a photocurable release agent suitable for flexible substrates. Background Art

[0002] A release agent is a type of separator film applied between a product and a mold to prevent the formed composite product from adhering to the mold, so that the product can be easily removed from the mold while ensuring the surface quality of the product and the integrity of the mold. Release agents are roughly divided into internal release agents added to the resin and external release agents using sprays. Generally, resin manufacturers and compounding material manufacturers add fatty acid esters, fatty acid metal salts, silicone resins, etc. as internal release agents to the resin. As external release agents, extrusion molding factories use spray-type release agents or release agents for mold surface treatment.

[0003] Currently, with the gradual expansion of applications, release agents are not only used on the surfaces of materials such as metals and plastics, but also on some flexible substrates such as flexible glass and hydrogel films. However, during the photocuring process, the monomer / prepolymer undergoes molecular chain shortening and an increase in crosslinking density during free radical polymerization, resulting in volume shrinkage (usually 2 - 10%). Flexible substrates (such as PET and PI films) have low moduli, and the shrinkage stress easily causes warping, delamination, or cracking of the release layer. The high crosslinking density leads to too high a modulus of the release layer (>1 GPa), poor compatibility with flexible substrates, and the generation of microcracks during bending. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method of a photocurable release agent suitable for flexible substrates. The present invention solves the problems of high shrinkage, low flexibility, and insufficient interfacial bonding force of the photocurable release agent for flexible substrates through dynamic covalent bond design, the synergistic effect of bio-inorganic composites, and refined process control.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a photocurable release agent suitable for flexible substrates, comprising the following steps:

[0007] S1. Mix epoxy acrylate and furfuryl methacrylate and carry out a first stirring reaction, then add bismaleimide and carry out a second stirring reaction to obtain a dynamic epoxy acrylate;

[0008] S2. Dissolve silk fibroin in formic acid, add nanocellulose and mix evenly, then prepare biofibers with a diameter of 100 - 200 nm through electrospinning and vacuum drying;

[0009] S3. Disperse SiO2 in ethanol, add KH-570 silane coupling agent, carry out reflux reaction, and centrifuge to obtain modified SiO2;

[0010] Mix the modified SiO2 with PDMS to obtain SiO2@PDMS composite;

[0011] S4. Add dynamic epoxy acrylate, flexible monomer PEG400DA, and antistatic agent to the reaction kettle. After stirring in a water bath at 60 °C, add biofiber and SiO2@PDMS composite, pre-disperse with a high-speed disperser, then perform three-roll grinding, and then add photoinitiator, leveling agent, and defoaming agent. Stir at low speed under dark conditions and then transfer the mixed solution to a vacuum degassing machine for treatment.

[0012] Preferably, the mass ratio of epoxy acrylate, furfuryl methacrylate, and bismaleimide in S1 is 10:(0.5 - 1):(0.5 - 1). In the present invention, by introducing reversible Diels-Alder (DA) dynamic covalent bonds, a reversible cross-linked network is formed after photocuring. The internal stress is released through stress-induced bond cleavage and recombination, while maintaining flexibility under high cross-linking density.

[0013] Preferably, the first stirring reaction temperature in S1 is 60 - 80 °C; the stirring reaction time is 2 - 3 h.

[0014] Preferably, the second stirring reaction temperature in S1 is 80 - 100 °C; the stirring reaction time is 1 - 2 h.

[0015] Preferably, the mass ratio of silk fibroin, formic acid, and nanocellulose in S2 is (8 - 10):100:(5 - 8).

[0016] Preferably, the parameters of electrospinning in S2 are: voltage 18 kV, flow rate 0.8 mL / h, and receiving distance 15 cm. Preferably, the mass ratio of SiO2, ethanol, and silane coupling agent in S3 is 10:100:(3 - 5).

[0017] Preferably, the mass ratio of modified SiO2 to PDMS prepolymer in S3 is 1:(3 - 5).

[0018] Preferably, the reflux reaction temperature in S3 is 80 °C and the time is 6 h.

[0019] Preferably, the mass ratio of dynamic epoxy acrylate, flexible monomer PEG400DA, antistatic agent, biofiber, SiO2@PDMS composite, photoinitiator, leveling agent, and defoaming agent in S4 is 80:(15 - 20):5:(10 - 15)(5 - 10):3:0.5:0.5.

[0020] Preferably, in S4, the water bath stirring temperature is 60-80°C, the time is 1-2 h, and the stirring speed is 200 rpm. By combining silk fibroin nanofibers with nano-SiO2, the present invention utilizes the low shrinkage characteristics of biomaterials and the rigid enhancement effect of inorganic fillers to reduce volume shrinkage and improve interfacial bonding force.

[0021] Preferably, in S4, the pre-dispersion rate is 5000 rpm and the time is 15 min; the three-roll grinding roller gap is 50 μm, and the grinding is carried out until the fineness is <5 μm.

[0022] Preferably, the parameters of the vacuum degassing machine are -0.095 MPa, 25°C, and the treatment time is 20 min.

[0023] It has at least the following beneficial technical effects:

[0024] By forming a cross-linked network of reversible Diels-Alder (DA) dynamic covalent bonds, the present invention can release internal stress through bond breakage and recombination, significantly reducing the volume shrinkage of traditional photocurable release agents caused by excessive cross-linking density, while maintaining flexibility and solving the problems of warping and delamination of flexible substrates caused by shrinkage stress. By using the electrospinning technique to prepare biofibers, the volume shrinkage of the release layer is effectively inhibited, and the interfacial bonding force is improved; the prepared modified SiO2 is compounded with PDMS, which not only enhances the rigidity of the release layer but also improves the matching with the flexible substrate through the flexibility of PDMS. Detailed Description of the Invention

[0025] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0026] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0028] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

[0029] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0030] As used in this invention, "room temperature" and "normal temperature" are both calculated as 25 ± 2°C unless otherwise specified.

[0031] Unless otherwise specified, the raw materials or instruments used in the following examples of this invention are all obtained commercially.

[0032] Example 1

[0033] This example provides a preparation method of a photocurable release agent applicable to a flexible substrate, including the following steps:

[0034] S1. Mix epoxy acrylate and furfuryl methacrylate and carry out the first stirring reaction at 70°C for 2.5 h, then add bismaleimide and carry out the second stirring reaction at 90°C for 1.5 h to obtain a dynamic epoxy acrylate;

[0035] The mass ratio of epoxy acrylate, furfuryl methacrylate, and bismaleimide is 10:0.8:0.8.

[0036] S2. Dissolve silk fibroin in formic acid, add nanocellulose and mix evenly, and then prepare biofibers with a diameter of 150 nm through electrospinning and vacuum drying;

[0037] The mass ratio of silk fibroin, formic acid, and nanocellulose is 9:100:6;

[0038] The parameters of electrospinning are: voltage 18 kV, flow rate 0.8 mL / h, and receiving distance 15 cm.

[0039] S3. Disperse SiO2 in ethanol, add KH-570 silane coupling agent, and reflux and react at 80 °C for 6 h, then centrifuge to obtain modified SiO2; the mass ratio of SiO2, ethanol, and silane coupling agent is 10:100:4.

[0040] Mix the modified SiO2 with PDMS to obtain the SiO2@PDMS composite; the mass ratio of the modified SiO2 to the PDMS prepolymer is 1:4.

[0041] S4. Add the dynamic epoxy acrylate, flexible monomer PEG400DA, and antistatic agent to the reaction kettle, stir at 70 °C and a stirring speed of 200 rpm in a water bath for 1 h, then add the biological fiber and the SiO2@PDMS composite, pre-disperse at 5000 rpm for 15 min using a high-speed disperser, then grind to a fineness of <5 μm by three-roll grinding, then add the photoinitiator TPO-L, leveling agent BYK-333, and defoaming agent BYK-055, stir slowly under dark conditions, and then transfer the mixed solution to a vacuum degassing machine with parameters of -0.095 MPa and 25 °C for 20 min.

[0042] The mass ratio of the dynamic epoxy acrylate, flexible monomer PEG400DA, antistatic agent, biological fiber, SiO2@PDMS composite, photoinitiator TPO-L, leveling agent BYK-333, and defoaming agent BYK-055 is 80:16:5:14:8:3:0.5:0.5.

[0043] Example 2

[0044] This example provides a preparation method of a photocurable release agent suitable for flexible substrates, including the following steps:

[0045] S1. Mix epoxy acrylate and furfuryl methacrylate, and carry out the first stirring reaction at 60 °C for 2 h, then add bismaleimide and carry out the second stirring reaction at 80 °C for 1 h to obtain the dynamic epoxy acrylate;

[0046] The mass ratio of epoxy acrylate, furfuryl methacrylate, and bismaleimide is 10:0.5:0.5.

[0047] Dissolve silk fibroin in formic acid, add nanocellulose and mix evenly, and then prepare biological fibers with a diameter of 100 nm by electrospinning and vacuum drying;

[0048] The mass ratio of silk fibroin, formic acid, and nanocellulose is 8:100:5;

[0049] The parameters of electrospinning are: voltage 18 kV, flow rate 0.8 mL / h, and receiving distance 15 cm.

[0050] S3. Disperse SiO2 in ethanol, add KH-570 silane coupling agent, and reflux and react at 80 °C for 6 h, then centrifuge to obtain modified SiO2; the mass ratio of SiO2, ethanol, and silane coupling agent is 10:100:3.

[0051] Mix the modified SiO2 with PDMS to obtain a SiO2@PDMS composite; the mass ratio of the modified SiO2 to the PDMS prepolymer is 1:3.

[0052] S4. Add the dynamic epoxy acrylate, flexible monomer PEG400DA, and antistatic agent to the reaction kettle, stir at 60 °C and a stirring speed of 200 rpm in a water bath for 1 h, then add the biofiber and SiO2@PDMS composite, pre-disperse at 5000 rpm for 15 min using a high-speed disperser, then grind to a fineness of <5 μm by three-roll grinding, then add the photoinitiator, leveling agent, and defoaming agent, stir slowly under light-shielded conditions, and then transfer the mixed solution to a vacuum degassing machine with parameters of -0.095 MPa and 25 °C for 20 min.

[0053] The mass ratio of the dynamic epoxy acrylate, flexible monomer PEG400DA, antistatic agent, biofiber, SiO2@PDMS composite, photoinitiator TPO-L, leveling agent BYK-333, and defoaming agent BYK-055 is 80:15:5:10:5:3:0.5:0.5.

[0054] Example 3

[0055] This example provides a preparation method of a photocurable release agent applicable to a flexible substrate, including the following steps:

[0056] S1. Mix epoxy acrylate and furfuryl methacrylate, and carry out the first stirring reaction at 80 °C for 3 h, then add bismaleimide and carry out the second stirring reaction at 100 °C for 2 h to obtain a dynamic epoxy acrylate;

[0057] The mass ratio of epoxy acrylate, furfuryl methacrylate, and bismaleimide is 10:1:1.

[0058] S2. Dissolve silk fibroin in formic acid, add nanocellulose and mix evenly, and then prepare biofibers with a diameter of 200 nm by electrospinning and vacuum drying;

[0059] The mass ratio of silk fibroin, formic acid, and nanocellulose is 10:100:8;

[0060] The parameters of electrospinning are: voltage 18 kV, flow rate 0.8 mL / h, and receiving distance 15 cm.

[0061] S3. Disperse SiO2 in ethanol, add KH-570 silane coupling agent, and reflux and react at 80 °C for 6 h, then centrifuge to obtain modified SiO2; the mass ratio of SiO2, ethanol, and silane coupling agent is 10:100:5.

[0062] Mix the modified SiO2 with PDMS to obtain the SiO2@PDMS composite; the mass ratio of the modified SiO2 to the PDMS prepolymer is 1:5.

[0063] S4. Add dynamic epoxy acrylate, flexible monomer PEG400DA, and antistatic agent to the reaction kettle, stir in a water bath at 80 °C with a stirring speed of 200 rpm for 2 h, then add biofiber and the SiO2@PDMS composite, pre-disperse at 5000 rpm for 15 min using a high-speed disperser, and then grind to a fineness of <5 μm through three-roll grinding. Then add photoinitiator, leveling agent, and defoaming agent, stir at low speed under dark conditions, and then transfer the mixed solution to a vacuum degassing machine with parameters set at -0.095 MPa and 25 °C for 20 min.

[0064] The mass ratio of dynamic epoxy acrylate, flexible monomer PEG400DA, antistatic agent, biofiber, SiO2@PDMS composite, photoinitiator TPO-L, leveling agent BYK-333, and defoaming agent BYK-055 is 80:20:5:15:10:3:0.5:0.5.

[0065] Comparative Example 1

[0066] The preparation method of this comparative example is the same as that of Example 1, except that in S4, an equal amount of epoxy acrylate is directly used.

[0067] Comparative Example 2

[0068] The preparation method of this comparative example is the same as that of Example 1, except that in S4, biofiber is not used.

[0069] Comparative Example 3

[0070] The preparation method of this comparative example is the same as that of Example 1, except that in S4, the SiO2@PDMS composite is not used.

[0071] Comparative Example 4

[0072] The preparation method of this comparative example is the same as that of Example 1, except that in S4, SiO2 particles are used.

[0073] Experimental Example

[0074] Detect the volume shrinkage rate, flexibility, and peel strength of the release agents obtained in the examples and comparative examples.

[0075] The release agent was coated on the flexible plastic film with a thickness of 20 microns for testing. The testing standard was: GB / T 27731. For the flexibility test: it was bent 1000 times at 90° to observe whether there was obvious separation. The test results are shown in Table 1.

[0076] Table 1

[0077]

[0078] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a photocurable release agent applicable to a flexible substrate, characterized in that, It includes the following steps: S1. Mix epoxy acrylate and furfuryl methacrylate, conduct the first stirring reaction, and then add bismaleimide to conduct the second stirring reaction to obtain a dynamic epoxy acrylate; S2. Dissolve silk fibroin in formic acid, add nanocellulose and mix evenly, then prepare biofibers with a diameter of 100 - 200 nm through electrospinning and vacuum drying; S3. Disperse SiO2 in ethanol, add KH-570 silane coupling agent, conduct a reflux reaction, and centrifuge to obtain modified SiO2; Mix the modified SiO2 with PDMS to obtain a SiO2@PDMS composite; S4. Add the dynamic epoxy acrylate, flexible monomer PEG400DA, and antistatic agent to a reaction kettle, stir in a 60°C water bath, then add the biofibers and SiO2@PDMS composite, pre-disperse using a high-speed disperser, then conduct three-roll grinding, then add a photoinitiator, leveling agent, and defoaming agent, stir at a low speed under light-shielded conditions, and then transfer the mixed solution to a vacuum degassing machine for treatment.

2. The preparation method according to claim 1, characterized in that, In the above S1, the mass ratio of epoxy acrylate, furfuryl methacrylate, and bismaleimide is 10:(0.5 - 1):(0.5 - 1).

3. The preparation method according to claim 1, characterized in that, In the above S2, the mass ratio of silk fibroin, formic acid, and nanocellulose is (8 - 10):100:(5 - 8).

4. The preparation method according to claim 1, wherein The parameters of the electrospinning in the above S2 are: voltage 18 kV, flow rate 0.8 mL / h, and receiving distance 15 cm.

5. The preparation method according to claim 1, wherein In the above S3, the mass ratio of SiO2, ethanol, and silane coupling agent is 10:100:(3 - 5).

6. The preparation method according to claim 1, wherein In the above S3, the mass ratio of the modified SiO2 to the PDMS prepolymer is 1:(3 - 5).

7. The preparation method according to claim 1, wherein In the above S4, the mass ratio of the dynamic epoxy acrylate, flexible monomer PEG400DA, antistatic agent, biofibers, SiO2@PDMS composite, photoinitiator, leveling agent, and defoaming agent is 80:(15 - 20):5:(10 - 15)(5 - 10):3:0.5:0.

5.

8. The preparation method according to claim 1, characterized in that, In the above S4, the temperature of the water bath stirring is 60 - 80°C, and the time is 1 - 2 h; the stirring speed is 200 rpm, and the time is 30 min.

9. The preparation method according to claim 1, characterized in that, The pre-dispersion rate is 5000 rpm, and the time is 15 min; the roll gap of the three-roll grinding is 50 μm, and the grinding is carried out until the fineness is <5 μm.

10. The preparation method according to claim 1, characterized in that, The parameters of the vacuum degassing machine are -0.095 MPa, 25°C, and the treatment time is 20 min.

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