Fluorine-free release agent, fluorine-free BOPET release film and application

Abstract

The invention belongs to the technical field of thin film materials, particularly discloses a fluoride-free release agent for a release film, and further discloses a fluoride-free BOPET release film and application thereof. According to the fluorine-free silicon-containing release agent for the release film, provided by the invention, an organic silicon modified polyurethane acrylate resin coating can be formed on the surface of a BOPET (Biaxially Oriented Polyethylene Terephthalate) base film, and then the release film with low surface tension and release force is prepared through ultraviolet curing.

Description

Technical Field

[0001] The invention belongs to the technical field of film materials, and in particular relates to a fluorine-free release agent for a release film, and also relates to a prepared fluorine-free BOPET release film and application thereof. Background Art

[0002] BOPET film (biaxially oriented polyester film) is a polyester film made of polyethylene terephthalate (PET) through melt extrusion, longitudinal stretching, transverse stretching, traction and winding. It has excellent mechanical properties, optical properties, heat resistance and chemical resistance. BOPET release film is obtained by coating the surface of BOPET film substrate with a release agent, so that it has extremely light and stable release force for different pressure-sensitive adhesives. It is a film material widely used in printing, packaging, ceramic capacitors, flexible circuits, automobiles, construction and medical fields. The requirements for release film in industry are good adhesion to the substrate and stable and good release force for pressure-sensitive adhesives.

[0003] At present, the commonly used release agents for preparing release films include long-chain alkyl release agents, fluorine release agents and silicone release agents. After curing, the surface energy of the coating of long-chain alkyl release agents is higher, and the anti-adhesion performance is lower, so the release force to pressure-sensitive adhesives is higher. Fluorine release agents are expensive, and fluorine-containing compounds are also prone to bioaccumulation and environmental pollution. Silicone release agents have low surface energy, hydrophobicity, high temperature resistance, and weather resistance. The surface tension of the prepared coating is very low and the release force to pressure-sensitive adhesives is low. Therefore, they have high application value in the field of release agents and can be used as ideal release agents.

[0004] However, most of the release films currently available on the market are prepared using traditional heat-curing silicone release agents, which have the following disadvantages: organic solvents such as toluene and gasoline are often used as diluents, and the solvents are easily volatilized by heat during heating and curing, causing environmental pollution, and rainbow patterns are also easily formed on the product surface.

[0005] In summary, both traditional fluorine-based release agents and traditional heat-curing silicone release agents will pollute the environment and do not meet the requirements of green and environmentally friendly production. Therefore, in the field of release film technology, it is urgent to develop a new type of release film that can achieve continuous production and meet the requirements of green and environmentally friendly production, and at the same time, the obtained release film has a stable and good release force. Summary of the invention

[0006] The object of the present invention is to provide a fluorine-free release agent for a release film. At the same time, the object of the present invention is also to provide a fluorine-free BOPET release film, and to provide a preparation method and application of the release film.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] In a first aspect, the present invention provides a fluorine-free release agent for a release film, wherein the raw materials for preparing the release agent include the following raw materials in parts by weight:

[0009]

[0010] As a preferred embodiment of the present invention, the raw materials for preparing the fluorine-free release agent for the release film include the following raw materials in parts by weight:

[0011]

[0012] 100 parts of isophorone diisocyanate

[0013] Polypropylene glycol 12-47 parts

[0014] 0.3 parts of dibutyltin dilaurate

[0015] Pentaerythritol acrylate 29 parts

[0016] 0.76 parts of 1,4-benzoquinone.

[0017] As an embodiment of the present invention, the polydimethylsiloxane is selected from bis-hydroxy mono-terminated polydimethylsiloxane and hydroxy di-terminated polydimethylsiloxane.

[0018] As an embodiment of the present invention, the pentaerythritol acrylate is selected from pentaerythritol triacrylate and pentaerythritol tetraacrylate.

[0019] In a second aspect, the present invention provides a fluorine-free BOPET release film, comprising a BOPET base film, a release layer is arranged on the BOPET base film, and the release layer is made of the release agent described in the present invention.

[0020] In a third aspect, the present invention provides a method for preparing a fluorine-free BOPET release film, comprising the steps of:

[0021] S1: Weigh the raw materials according to the composition of the release agent, mix polydimethylsiloxane with isophorone diisocyanate and polypropylene glycol, and react them under an inert atmosphere and the catalysis of dibutyltin dilaurate to generate a precursor mixture;

[0022] S2: adding crosslinking agents pentaerythritol acrylate and 1,4-benzoquinone to the precursor mixture obtained in step S1, stirring and reacting to obtain a release agent prepolymer;

[0023] S3: The release agent prepolymer is UV cured on the surface of the BOPET base film to prepare a fluorine-free BOPET release film.

[0024] As an embodiment of the present invention, step S3 includes: mixing the release agent prepolymer with ethyl acetate and a photoinitiator, and stirring evenly with a magnetic force under light-proof conditions to prepare a photosensitive solution;

[0025] The photosensitive solution is coated on a BOPET base film (surface wetting tension corona value ≥ 52 mN / m) that has been previously corona-treated, and cured using a UV light curing machine to prepare a fluorine-free BOPET release film.

[0026] As an embodiment of the present invention, the photoinitiator is selected from photoinitiator 1173, photoinitiator 184 and photoinitiator 659.

[0027] As an embodiment of the present invention, in step S1, the reaction temperature is 70-80°C.

[0028] As an embodiment of the present invention, in step S2, the reaction temperature is 60-68°C.

[0029] In a fourth aspect, the present invention provides an application of a fluorine-free BOPET release film, the application of the fluorine-free BOPET release film of the present invention or the release film obtained by the preparation method of the present invention in printing, packaging, ceramic capacitors, flexible circuits, automobiles, construction, and medical treatment; or, the application of the fluorine-free BOPET release film of the present invention or the release film obtained by the preparation method of the present invention as a waterproof material.

[0030] The present invention provides a fluorine-free silicon-containing release agent for a release film. The release agent is used to prepare a fluorine-free BOPET release film using an ultraviolet (UV) curing method. Compared with fluorine-containing release agents and traditional thermal curing technology, the release agent provided by the present invention is green, environmentally friendly and pollution-free. The process temperature and energy consumption are low when preparing the release film, and the curing process is efficient and fast, which provides a new idea for preparing the release film. The release film prepared by the present invention has a light release force and low surface energy, and has good easy peeling and waterproof properties, which can further broaden the application field of traditional silicone release films.

[0031] The fluorine-free silicon-containing release agent for release film provided by the present invention can form a silicone-modified polyurethane acrylate resin coating on the surface of a BOPET base film, and then be cured by ultraviolet light to prepare a release film with low surface tension and release force.

[0032] Taking the release agent raw materials of dihydroxy mono-terminated polydimethylsiloxane (PDMS-OH), isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), polypropylene glycol (PPG), pentaerythritol triacrylate (PETA), and 1,4-benzoquinone (BQ) as an example, when the release agent of the present invention is used to prepare a release film, the dihydroxy mono-terminated polydimethylsiloxane is firstly blocked with isophorone diisocyanate, and a polyurethane acrylic resin is synthesized as a prepolymer of the release film coating; the reactions involved are as follows:

[0033] Synthesis of Precursor 1:

[0034]

[0035] Synthesis of Precursor 2:

[0036]

[0037] The mixture containing the precursor 1 and the precursor 2 is further prepared to obtain a prepolymer containing the compounds of the structural formulas shown in Formula 1 and Formula 2:

[0038]

[0039] Afterwards, the synthesized prepolymer is UV-cured on the surface of the BOPET base film to prepare a release film. The specific steps are: the synthesized prepolymer is mixed with ethyl acetate (EA) and 2-hydroxy-2-methylpropiophenone (photoinitiator 1173), and magnetically stirred evenly under light-proof conditions to prepare a photosensitive solution; the photosensitive solution is evenly coated on the BOPET base film that has been corona-treated in advance, and after standing for 10 minutes, it is cured using a UV light curing machine to obtain a release film.

[0040] The main body of the organosilicon release agent used in the preparation of the release film of the present invention is polydimethylsiloxane, which avoids the use of fluorine-containing substances and can effectively prevent fluorine-containing substances from causing harm to the environment and bioaccumulation. The release film of the present invention adopts ultraviolet light curing technology, which can effectively reduce the emission of volatile solvents compared with traditional thermal curing technology, and the process is more green and environmentally friendly. The preparation process adopted by the release film of the present invention uses ultraviolet light curing technology, and the curing process is more efficient and rapid, and the energy consumption of the curing process is low, which is convenient for large-scale streamlined operation, and provides a new idea for preparing the release film. The release film prepared by the present invention has a lighter release force and low surface energy, and has the characteristics of easy peeling and waterproofness, which further broadens the application field of traditional organosilicon release films. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described in detail below. It should be understood by those skilled in the art that the specific implementation is only to help understand the present invention and should not be regarded as a specific limitation of the present invention.

[0042] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art.

[0043] In the following examples, the BOPET base film used is a biaxially oriented polyethylene terephthalate film, which is obtained by extruding, casting, and biaxially stretching PET slices, using the existing conventional BOPET film process, and is provided by Kanghui Nantong New Material Technology Co., Ltd.

[0044] Unless otherwise specified, other raw materials are commercially available conventional products and can be purchased.

[0045] The following is a detailed explanation through specific examples.

[0046] Example 1

[0047] This embodiment provides a fluorine-free release agent, the weight parts of which are arranged as follows:

[0048]

[0049] A release film was prepared by using the fluorine-free release agent provided in this embodiment. The preparation process of the release film is as follows:

[0050] (1) Weigh each raw material according to the composition of the release agent, add dihydroxy mono-terminated polydimethylsiloxane (PDMS-OH) into a four-necked flask reactor connected to a thermometer, a stirring device, and a condenser reflux tube, set the temperature to 60°C, then add isophorone diisocyanate (IPDI) and polypropylene glycol (PPG), mix evenly, introduce nitrogen, add catalyst dibutyltin dilaurate (DBTDL) after the system temperature reaches 75°C, stir and react for 2h, then keep warm for 1h, without stirring during the keeping warm process, by keeping warm to ensure the activity of the reactants and reduce the occurrence of side reactions, to produce a mixed product of precursor 1 and precursor 2 (the structural formulas of precursor 1 and precursor 2 are as described above);

[0051] (2) Then, pentaerythritol triacrylate (PETA) and 1,4-benzoquinone (BQ) are added to the reaction system obtained by the reaction in step (1), and the system is cooled to 65°C and stirred for 1 hour. During this period, the change in the content of -NCO groups is detected by toluene-di-n-butylamine titration method until the theoretical value is reached and the reaction end point is determined. The reaction is terminated to obtain a prepolymer containing the structural compounds shown in Formula 1 and Formula 2 (the structural formulas of Formula 1 and Formula 2 are as described above). The theoretical value is the initial NCO value measured first, and then the theoretical value should be 0.5% of the initial NCO measured value. At this time, the number of unreacted NCO groups in the reaction system has approached 0. The determination of the NCO value is to react di-n-butylamine with the NCO group, and then titrate the excess di-n-butylamine with a hydrochloric acid standard solution to calculate the NCO content in the sample. In addition, the NCO content in the reactant can be regularly detected by infrared spectroscopy, and the reaction is stopped when it reaches the predetermined target.

[0052] (3) UV curing the synthesized prepolymer on the surface of the BOPET base film to prepare a release film, specifically: weighing the prepolymer prepared in step (2), mixing it with ethyl acetate (EA) and photoinitiator 1173 (2-hydroxy-2-methylpropiophenone), and stirring it evenly with a magnetic force under light-proof conditions to prepare a photosensitive solution, wherein the mass percentage concentration of the prepolymer is 5%;

[0053] The photosensitive solution was evenly coated on the BOPET base film that had been corona treated in advance (the surface wetting tension corona value of the BOPET base film after corona treatment was ≥52mN / m), allowed to stand for 10 minutes, and then cured for 30 seconds using a UV light curing machine (power 1kw) to obtain a release film.

[0054] Example 2

[0055] This embodiment provides a fluorine-free release agent, the weight parts of which are arranged as follows:

[0056]

[0057] A release film was also prepared using the fluorine-free release agent provided in this embodiment. The preparation process of the release film was similar to that of Example 1.

[0058] Example 3

[0059] This embodiment provides a fluorine-free release agent, the weight parts of which are arranged as follows:

[0060]

[0061] A release film was also prepared using the fluorine-free release agent provided in this embodiment. The preparation process of the release film was similar to that of Example 1.

[0062] Example 4

[0063] This embodiment provides a fluorine-free release agent, the weight parts of which are arranged as follows:

[0064]

[0065] A release film was also prepared using the fluorine-free release agent provided in this embodiment. The preparation process of the release film was similar to that of Example 1.

[0066] The performance of the release films provided in the above Examples 1-4 was tested, as follows.

[0067] 1. Release force test

[0068] Release force, also known as peeling force, is an important performance indicator of release materials. Test method: Cut the release film sample into 25mm×200mm strips, stick the standard test tape (Tesa 7475 tape) on the sample to be tested, and press back and forth with a standard pressure roller several times to make the tape and sample in close contact. Place it at room temperature for 20 minutes, then use a clamp to fix the sample on an electronic tensile testing machine for a 180° peeling test. The test speed is 300mm / min, and the test result is the release force; place it at 70℃ for 24 hours and then test it again. The result is the aged release force.

[0069] 2. Residual Adhesion Test

[0070] Test method: Cut the sample to be tested and Teflon film into strips of 25mm×200mm, stick 31B tape on the surface of both, use standard pressure roller to press back and forth several times, then use standard pressure strip to press it flat, place it in a 70℃ oven for 24h, then remove the load and place it in standard environment for 2h. Peel the tape off the sample to be tested and stick it on the non-corona of blank PET release film, press it twice with pressure roller, and do the same operation on Teflon film as blank standard sample. Then use peel force tester to test, the residual adhesion rate calculation formula is:

[0071] Residual adhesion % = force required to peel off the test sample ÷ force required to peel off the blank standard sample × 100%.

[0072] 3. Contact angle test

[0073] The waterproof performance is judged by the size of the contact angle. The test method is: the contact angle of the release film sample surface is tested by the droplet method. First, the release film sample is spread on a glass slide, and 5μL of water droplets are added to the film surface, and the contact angle is measured by a contact angle meter.

[0074] The test results of the above performance tests are specifically shown in Table 1 below.

[0075] Table 1

[0076]

[0077] It can be seen from the data in Table 1 that the release films prepared in Examples 1-4 of the present invention all have good release force, aged release force and residual adhesion rate, among which the release film prepared in Example 3 has the best performance. The 20-min release force can be as low as 5.8 cN / 2.5 cm, the 24-h aged release force is only 8.2 cN / 2.5 cm, the residual adhesion rate is as high as 99%, and the contact angle is close to 108°, indicating that the prepared release film not only has good peeling performance, but also has good waterproof performance, which can meet the use requirements of the release film in various scenarios and can broaden the application in the field of waterproof materials.

[0078] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A fluorine-free release agent, characterized in that: The preparation raw materials include the following raw materials in parts by weight:

2. The fluorine-free release agent according to claim 1, characterized in that: The preparation raw materials include the following raw materials in parts by weight:

3. The fluorine-free release agent according to claim 1 or 2, characterized in that: The polydimethylsiloxane is selected from dihydroxy mono-terminated polydimethylsiloxane and hydroxy di-terminated polydimethylsiloxane; and the pentaerythritol acrylate is selected from pentaerythritol triacrylate and pentaerythritol tetraacrylate.

4. A fluorine-free BOPET release film, characterized in that: The invention comprises a BOPET base film, on which a release layer is arranged, and the release layer is made of the release agent according to any one of claims 1 to 3.

5. A method for preparing the fluorine-free BOPET release film according to claim 4, characterized in that: Includes steps: S1: Weigh the raw materials according to the composition of the release agent, mix polydimethylsiloxane with isophorone diisocyanate and polypropylene glycol, and react them under an inert atmosphere and the catalysis of dibutyltin dilaurate to generate a precursor mixture; S2: adding crosslinking agents pentaerythritol acrylate and 1,4-benzoquinone to the precursor mixture obtained in step S1, stirring and reacting to obtain a release agent prepolymer; S3: The release agent prepolymer is UV cured on the surface of the BOPET base film to prepare a fluorine-free BOPET release film.

6. The preparation method according to claim 5, characterized in that: Step S3 includes: mixing the release agent prepolymer with ethyl acetate and a photoinitiator, and evenly stirring the mixture under light-proof conditions to obtain a photosensitive solution; coating the photosensitive solution on a BOPET base film that has been previously corona-treated, and curing the solution using a UV curing machine to obtain a fluorine-free BOPET release film.

7. The preparation method according to claim 6, characterized in that: The photoinitiator is selected from photoinitiator 1173, photoinitiator 184 and photoinitiator 659.

8. The preparation method according to any one of claims 5 to 7, characterized in that: In step S1, the reaction temperature is 70-80°C.

9. The preparation method according to claim 8, characterized in that: In step S2, the reaction temperature is 60-68°C.

10. Application of the fluorine-free BOPET release film according to claim 4 or the release film obtained by the preparation method according to any one of claims 5 to 9 in printing, packaging, ceramic capacitors, flexible circuits, automobiles, construction, and medical treatment; or, application as a waterproof material.

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