Ultra-light release film as well as preparation method and application thereof

Abstract

The invention provides an ultralight release film as well as a preparation method and application thereof. The ultra-light release film comprises a micro-convex PET (Polyethylene Terephthalate) base film and a release layer formed by coating a release agent on the PET base film layer, the release agent is prepared from the following raw materials in parts by weight: 60 to 100 parts of organosiloxane resin A, 10 to 50 parts of organosiloxane resin B, 0.05 to 0.2 part of an inhibitor, 0.55 to 1.45 parts of a crosslinking agent containing silicon-hydrogen bonds, 0.2 to 0.5 part of an adhesion additive, 1.55 to 3.45 parts of a platinum complex catalyst and 300 to 1200 parts of an organic solvent. The anti-aging coating has the advantages of excellent anti-aging property, excellent residual adhesion rate and no powder falling risk.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of release film, in particular to an ultralight release film and a preparation method and application thereof. BACKGROUND

[0002] The release film is a kind of film with separation on the surface, and its core function is to easily peel off after being attached to the pressure-sensitive adhesive or optical adhesive of the protected material without damaging the adhesive.

[0003] The ultralight release film of the prior art generally has the following technical problems: (1) Aging problem: the release force of the release film will increase significantly over time during the storage process and the storage process after being attached to the pressure-sensitive adhesive, which is called "aging". The peeling force of the aged release film is too large, which will cause peeling difficulty during use, and even cause tearing film noise, adhesive residue (residual glue) and other phenomena.

[0004] (2) Low residual adhesion rate: the substances not fully cross-linked in the release layer will migrate to the back of the release film and the attached pressure-sensitive adhesive, which will not only reduce the pulling force of the back of the release film and make it unable to adapt to the automatic waste removal of the die-cutting equipment, but also will damage the adhesion of the pressure-sensitive adhesive to different degrees after peeling, resulting in a decrease in adhesion and affecting the subsequent bonding effect. This is a fatal defect for application scenarios with extremely high adhesion requirements (such as optical adhesive).

[0005] (3) Difficulty in balancing: traditional technical means often cannot solve the contradiction between "low aging" and "high residual adhesion rate" at the same time. For example, increasing the cross-linking density to improve the residual adhesion rate will often exacerbate the aging phenomenon; and reducing the cross-linking density to suppress aging will also result in too much residual substance not participating in cross-linking, which will reduce the residual adhesion rate.

[0006] (4) Silicon powder easy to transfer: due to the addition of light peeling agent, high coating amount, micro-concave process and other reasons, the ultralight release film must add anti-sticking agent to prevent the release surface from sticking; the anti-sticking agent is inorganic or organic silicon dioxide particles after surface treatment, also known as "silicon powder", which does not participate in the curing reaction of the release agent and is added in the release layer in a physical mixing manner. Therefore, the anti-sticking agent may fall off and transfer to the optical adhesive to cause particle points in the attachment, i.e. the "powder falling" problem, which will affect the adhesion, transmittance, haze and other indicators of the adhesive surface, and also affect the visual effect after attachment.

[0007] Therefore, it is urgent to develop an ultralight release film without silicon powder and with excellent anti-aging performance and high residual adhesion rate. SUMMARY

[0008] This invention addresses the problems of existing ultralight release films, such as the presence of silicon powder, poor aging performance, and inability to maintain a high residual adhesion rate, by providing an ultralight release film, its preparation method, and its application.

[0009] The technical method of the present invention is as follows: In a first aspect, the present invention provides an ultralight release film, comprising a micro-protruding PET base film and a release layer formed by coating a release agent onto the PET base film layer; the release agent is prepared from the following raw materials in parts by weight: 60-100 parts of organosiloxane resin A, 10-50 parts of organosiloxane resin B, 0.05-0.2 parts of inhibitor, 0.55-1.45 parts of a crosslinking agent containing silane-hydrogen bonds, 0.2-0.5 parts of adhesion additive, 1.55-3.45 parts of platinum complex catalyst, and 300-1200 parts of organic solvent. Here, the release force of the ultralight release film is in the range of 1-3 gf / 25mm.

[0010] The present invention has the following advantages: (i) Excellent anti-aging properties: By adjusting the ratio of the two organosiloxane resins in the formula, the surface energy of the release layer is controlled so that the surface tension is 20-22 mN / m; at the same time, a light peel force modifier is selectively added to improve the anti-aging properties of the release layer, so that the release force does not increase significantly after the pressure-sensitive adhesive is applied to the release surface and baked at 70℃ for 28 days.

[0011] (ii) Excellent residual adhesion: By adjusting the proportion of vinyl groups in the formulation and the amount of crosslinking agent containing silane bonds, the crosslinking density of the release layer is controlled, the residue of uncrosslinked substances is reduced, the back tensile strength is significantly improved, and it can be adapted to the automatic waste removal of die-cutting equipment; at the same time, the migration of the adhesive surface is significantly reduced, and the adhesion of the pressure-sensitive adhesive is almost not damaged.

[0012] (iii) No risk of powder shedding: By adjusting the formula, the formula does not contain silicon powder or other non-reactive particles, thus avoiding the risk of silicon powder transfer in the release layer from the root and not affecting the visual effect after the optical adhesive is bonded.

[0013] Preferably, the micro-protruding PET base film is formed by adding specific microparticles to the PET base film layer. Here, the specific microparticles include inorganic microparticles and / or organic microparticles. The inorganic microparticles may be silica. The specific microparticles can effectively increase the surface roughness of the film by forming a micro-protrusion structure on the film surface; at the same time, the particle size, surface modification, and other characteristics of the microparticles themselves have a certain influence on the roughness of the micro-protrusions and the adhesion effect of the microparticles in the film.

[0014] Preferably, the organosiloxane resin A is a modified polydimethylsiloxane, and the organosiloxane resin B is a mixed cyclic form of dimethylsiloxane. Specifically, the modified polydimethylsiloxane can be a vinyl-terminated polydimethylsiloxane. Further, the organosiloxane resin A includes MQ resin. This invention achieves a light release force by adjusting the viscosity and crosslinking density through adjusting the ratio of the two resins. Preferably, the light release force and the stability of the release force can be further adjusted using MQ resin.

[0015] Preferably, the platinum complex catalyst is platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane, which is formed by complexing chloroplatinic acid with a vinyl-terminated siloxane (such as tetramethyldisiloxane). It has high reactivity, storage stability, and good compatibility with various polysiloxanes. More preferably, the amount of platinum complex catalyst added is 3% to 7% of the total solid mass of the release agent.

[0016] Preferably, the crosslinking agent containing silane bonds is polymethylhydrosiloxane. More preferably, the amount of crosslinking agent containing silane bonds added is 1% to 3% of the total solid mass of the release agent.

[0017] Preferably, the inhibitor is an alkynyl alcohol or a carboxylic anhydride. The inhibitor of the present invention works by preemptively forming a coordination group with the platinum catalyst, thereby slowing down or inhibiting the reaction process. Specifically, the alkynyl alcohol includes one or more of propynyl alcohol, forcalenyl diol, and 1-ethynylcyclohexanol.

[0018] Preferably, the adhesion additive is a polysiloxane containing silanol groups. One end of the adhesion additive of the present invention can react with modified polydimethylsiloxane, and the other end can react with active free groups generated on the substrate surface by corona treatment, thereby achieving an anchoring effect.

[0019] Preferably, the organic solvent includes one or more of toluene, petroleum ether, butanone, isopropanol, and ethyl acetate. The mass ratio of toluene, petroleum ether, butanone, isopropanol, and ethyl acetate can be 0-2:0-2:0-2:0-2:0-2.

[0020] The release film of the present invention, after aging at 70°C for 28 days with Tesa7475 tape, has a release force of no more than 4 gf / 25mm, the release film, after aging at 70°C with Nitto31B tape, has a residual adhesion rate of more than 80%, and the release film, after aging at 70°C with Tesa7475 tape, has a tensile strength of more than or equal to 1200 gf / 25mm for 20 minutes.

[0021] Secondly, the present invention provides a method for preparing an ultralight release membrane, the method comprising: (1) The organosiloxane resin A, organosiloxane resin B, inhibitor, crosslinking agent containing silane-hydrogen bonds, adhesion additive, platinum complex catalyst and organic solvent are mixed and stirred in sequence according to the formula to obtain release agent; The PET base film with micro-protrusions was subjected to corona treatment to obtain a corona-treated PET base film; (2) Using a micro-grooving coating process, the release agent is coated on the corona surface of the corona-treated PET base film, and then baked and cured to form a release layer, thus obtaining an ultra-light release film.

[0022] Preferably, in step (1), the stirring speed is 450-550 r / min and the time is 2-4 min. For example, the stirring speed is 410 r / min, 450 r / min, or 520 r / min, and the time is 3 min. This invention achieves better mixing results by reasonably controlling the stirring speed and time.

[0023] Preferably, in step (1), the preparation of the micro-protruding PET base film includes adding inorganic microparticles to the PET film material formulation, melting and extruding, and then stretching into a film.

[0024] Preferably, in step (2), the dry coating weight of the microgravure coating process is 0.8-1.2 g / m². 2 The dry weight of this invention is less than 0.8 g / m³. 2 If the release layer is too thin, it will not reach the release force range required for ultralight applications, and the dry weight will be higher than 1.2 g / m². 2 Problems such as poor curing and release layer adhesion are prone to occur.

[0025] Preferably, in step (2), the baking temperature is 145-155℃ and the time is 40-60s. For example, the baking temperature is 147℃ or 150℃ and the time is 40s or 50s. By setting appropriate baking temperature and time, the present invention not only facilitates the crosslinking of raw materials, but also ensures good crosslinking effect and moderate speed, ultimately resulting in better overall performance of the release layer.

[0026] Preferably, in step (1), an antistatic agent is coated on the corona-treated PET base film to prevent static electricity from attracting dust during subsequent production.

[0027] Thirdly, the present invention provides an application of an ultralight release film in optical adhesives, pressure-sensitive adhesive products or industrial tapes.

[0028] The beneficial effects of this invention are: I. This invention possesses superior anti-aging properties: By adjusting the ratio of the two organosiloxane resins in the formula, the surface energy of the release layer is controlled, maintaining a surface tension of 20-22 mN / m. Simultaneously, the selective addition of a light peel force modifier improves the anti-aging performance of the release layer, ensuring that the release force does not significantly increase after 28 days of baking at 70°C following the bonding of the pressure-sensitive adhesive to the release surface. Excellent residual adhesion: By adjusting the ratio of vinyl groups and the amount of crosslinking agent containing silane bonds in the formula, the crosslinking density of the release layer is controlled, reducing the residue of uncrosslinked substances and significantly improving the back-side tensile strength, allowing for automatic waste removal in die-cutting equipment. Simultaneously, it significantly reduces adhesive migration, almost without compromising the adhesiveness of the pressure-sensitive adhesive. No risk of powder shedding: By adjusting the formula, it eliminates the presence of silicon powder or other non-reactive particles, fundamentally avoiding the risk of silicon powder transfer from the release layer, thus preserving the visual effect after optical adhesive bonding.

[0029] 2. The ultralight release film of the present invention does not contain silicon powder or other non-reactive particulate matter in its formulation. After being bonded to pressure-sensitive adhesive and stored for a long time, it exhibits a small change rate in release force, can be cleanly peeled off from various high-performance pressure-sensitive adhesives, and maintains a residual adhesion rate of over 80%. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0031] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0032] Example 1 This embodiment provides an ultralight release film, which is prepared by mixing 90 parts by weight of organosiloxane resin A, 10 parts by weight of organosiloxane resin B, 0.1 parts by weight of inhibitor, 1 part by weight of crosslinking agent containing silane-hydrogen bonds, 0.3 parts by weight of adhesion additive, and 2.5 parts by weight of platinum complex catalyst, and then adding them sequentially to 400 parts by weight of organic solvent (100 parts by weight of toluene, 200 parts by weight of petroleum ether, and 100 parts by weight of methyl ethyl ketone) to obtain the release agent.

[0033] Among them, organosiloxane resin A is vinyl-terminated polydimethylsiloxane, organosiloxane resin B is a mixed cyclic form of dimethylsiloxane, the inhibitor is 1-ethynylcyclohexanol, the adhesion additive is polysiloxane containing silanol, the organic solvents include toluene, petroleum ether, butanone, isopropanol, and ethyl acetate, and the platinum complex catalyst is platinum(0)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane.

[0034] The specific preparation method includes the following steps: (1) Base film preparation: Specific microparticles are added to the PET film material formulation, melt extruded and stretched into a film to obtain a micro-protruding PET base film. The micro-protruding PET base film is subjected to corona treatment (surface tension greater than 50 mN / m) and then coated with an antistatic layer to obtain an antistatic film for later use.

[0035] (2) Preparation of release agent: In the order of mass parts, add organosiloxane resin A, organosiloxane resin B, inhibitor, crosslinking agent containing silane-hydrogen bonds, adhesion additive, platinum complex catalyst to organic solvent. Stir evenly (500r / min, 3min) after each addition to obtain the prepared release agent.

[0036] (3) Processing conditions: The prepared release agent is applied to the antistatic film using a micro-gravure process (coating dry weight is 1.0 g / m²), and then baked and cured (150℃, 50 s) to obtain an ultra-light release film.

[0037] Example 2 This embodiment provides an ultralight release film, using the same formulation and preparation method as in Example 1, except that: the release agent comprises 80 parts by weight of organosiloxane resin A, 20 parts by weight of organosiloxane resin B, 0.1 parts by weight of inhibitor, 1 part by weight of crosslinking agent containing silane-hydrogen bonds, 0.3 parts by weight of adhesion additive, and 2.5 parts by weight of platinum complex catalyst, which are then added sequentially to 400 parts by weight of organic solvent.

[0038] Example 3 This embodiment provides an ultralight release film, using the same formulation and preparation method as Example 1, except that: the release agent comprises 70 parts by weight of organosiloxane resin A, 30 parts by weight of organosiloxane resin B, 0.1 parts by weight of inhibitor, 1 part by weight of crosslinking agent containing silane-hydrogen bonds, 0.3 parts by weight of adhesion additive, and 2.5 parts by weight of platinum complex catalyst, which are then added sequentially to 400 parts by weight of organic solvent.

[0039] Example 4 This embodiment provides an ultralight release film, which uses the same formulation and preparation method as in Example 1, except that: the release agent includes 60 parts by weight of organosiloxane resin A, 40 parts by weight of organosiloxane resin B, 0.1 parts by weight of inhibitor, 1 part by weight of crosslinking agent containing silane-hydrogen bonds, 0.3 parts by weight of adhesion additive, and 2.5 parts by weight of platinum complex catalyst, which are then added sequentially to 400 parts by weight of organic solvent.

[0040] Example 5 This embodiment provides an ultralight release film, using the same formulation and preparation method as Example 1, except that: the release agent includes 50 parts by weight of organosiloxane resin A, 50 parts by weight of organosiloxane resin B, 0.1 parts by weight of inhibitor, 1 part by weight of crosslinking agent containing silane-hydrogen bonds, 0.3 parts by weight of adhesion additive, and 2.5 parts by weight of platinum complex catalyst, which are then added sequentially to 400 parts by weight of organic solvent.

[0041] Comparative Example 1: This embodiment provides an ultralight release film, which uses the same formulation and preparation method as in Example 1, except that: organosiloxane resin A is used as the main component alone, and organosiloxane resin B is not used.

[0042] Comparative Example 2: This embodiment provides an ultralight release film, which uses the same formulation and preparation method as in Example 1, except that: organosiloxane resin B is used as the main component, and organosiloxane resin A is not used.

[0043] Comparative Example 3: This embodiment provides an ultralight release membrane, which uses the same formulation and preparation method as in Example 1, except that no inhibitor is added to the formulation.

[0044] Comparative Example 4: This embodiment provides an ultralight release membrane, which uses the same formulation and preparation method as in Example 1, except that the amount of crosslinking agent containing silane bonds is 0.5 parts.

[0045] Comparative Example 5: This embodiment provides an ultralight release membrane, which uses the same formulation and preparation method as in Example 1, except that the amount of crosslinking agent containing silane bonds is 1.5 parts.

[0046] Comparative Example 6: This embodiment provides an ultralight release membrane, which uses the same formulation and preparation method as in Example 1, except that the amount of platinum complex catalyst used is 1.5 parts.

[0047] Comparative Example 7: This embodiment provides an ultralight release membrane, which uses the same formulation and preparation method as in Example 1, except that the amount of platinum complex catalyst used is 3.5 parts.

[0048] The release films prepared in Examples 1-5 and Comparative Examples 1-7 were subjected to performance tests according to standard GB / T25256-2010. The test items included: release force at 20 min, release force at 23℃ / 24 h, release force at 70℃ / 24 h, residual adhesion at 23℃ / 24 h, residual adhesion at 70℃ / 24 h, back tensile strength, and coating dry weight (X-ray fluorescence method). The test results are shown in Table 1. Table 1 Test data of the examples and comparative examples The samples obtained in Example 3 were bonded to Tesa7475 tape and tested for release force after aging. Release force at 23℃ / (24h, day 03, day 07, day 14, day 21, day 28) and at 70℃ / (24h, day 03, day 07, day 14, day 21, day 28) were tested according to standard GB / T25256-2010. The results are shown in Table 2. Table 2. Aging data of Example 3 Test results show that this invention, through specific base film, additive ratio, solvent ratio, process and curing conditions, successfully prepared an ultralight release film with low aging creep and high residual adhesion, and the formulation does not contain inorganic particles or other non-reactive particles, perfectly solving industry pain points and suitable for applications such as optical adhesive die-cutting and high-performance industrial tapes.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An ultralight release film, characterized in that, The release agent comprises a micro-protruding PET base film and a release layer formed by coating the PET base film layer with a release agent; the release agent is prepared from the following raw materials in parts by weight: 60-100 parts of organosiloxane resin A, 10-50 parts of organosiloxane resin B, 0.05-0.2 parts of inhibitor, 0.55-1.45 parts of crosslinking agent containing silane-hydrogen bonds, 0.2-0.5 parts of adhesion additive, 1.55-3.45 parts of platinum complex catalyst, and 300-1200 parts of organic solvent.

2. The ultralight release film according to claim 1, characterized in that, The micro-protrusions in the PET base film are formed by adding specific microparticles to the PET base film layer. These specific microparticles include inorganic microparticles and / or organic microparticles, with the inorganic microparticles being silicon dioxide.

3. The ultralight release film according to claim 1, characterized in that, The organosiloxane resin A is a modified polydimethylsiloxane, and the organosiloxane resin B is a dimethylsiloxane mixed cyclic compound.

4. The ultralight release film according to claim 1, characterized in that, The platinum complex catalyst is platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane; The crosslinking agent containing silane bonds is polymethylhydrosiloxane; The inhibitor is an alkynyl alcohol or a carboxylic anhydride; The adhesion additive is a polysiloxane containing silanol groups; The organic solvent includes one or more of toluene, petroleum ether, butanone, isopropanol, and ethyl acetate.

5. A method for preparing the ultralight release film according to any one of claims 1-4, characterized in that, The preparation method includes: (1) The organosiloxane resin A, organosiloxane resin B, inhibitor, crosslinking agent containing silane-hydrogen bonds, adhesion additive, platinum complex catalyst and organic solvent are mixed and stirred in sequence according to the formula to obtain release agent; The PET base film with micro-protrusions was subjected to corona treatment to obtain a corona-treated PET base film; (2) Using a micro-grooving coating process, the release agent is coated on the corona surface of the corona-treated PET base film, and then baked and cured to form a release layer, thus obtaining an ultra-light release film.

6. The preparation method according to claim 5, characterized in that, In step (1), the stirring speed is 450-550 r / min and the time is 2-4 min.

7. The preparation method according to claim 5, characterized in that, In step (2), the dry coating weight of the microgravure coating process is 0.8-1.2 g / m². 2 .

8. The preparation method according to claim 5, characterized in that, In step (2), the baking temperature is 145-155℃ and the time is 40-60s.

9. The preparation method according to claim 5, characterized in that, In step (1), an antistatic agent is coated on the corona-treated surface of the PET base film.

10. The application of the ultralight release film according to any one of claims 1-4 in optical adhesives, pressure-sensitive adhesive products or industrial tapes.

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