An adhesive resin composition, a surface protective film, and use thereof

Abstract

The present application relates to the technical field of protective film, and particularly relates to an adhesive resin composition, a surface protective film and application thereof, the adhesive resin composition comprises a crosslinked network phase formed by a polymer, a tackifying wetting phase formed by a fully hydrogenated petroleum resin, and a nano-protrusion phase with a lateral size of 50nm-200nm formed at crosslinking points of the crosslinked network phase; the polymer is a hydrogenated block copolymer with physical crosslinking capability. The adhesive resin composition provided by the present application constructs a three-phase microstructure of "tackifying wetting phase-crosslinked network phase-nano-protrusion phase", and a surface protective film using the adhesive resin composition can autonomously respond to different surface topologies, and realize general protective properties of optical film haze and mirror.

Description

An adhesive resin composition, a surface protective film and its applications Technical Field

[0001] This invention relates to the field of protective film technology, specifically to an adhesive resin composition, a surface protective film, and its application. The adhesive resin composition is suitable for surface protective films of optical films with different surface states. Background Technology

[0002] Surface protective film is a thin film used to protect the surface of vulnerable objects. Its purpose is to provide temporary surface protection during production, processing, transportation, and storage. Because surface protective film itself does not contain adhesive, no adhesive residue will appear on the protected product surface, and its high transparency facilitates observation of the surface condition of the protected product. With the continuous development of the global display industry, the demand for optical films, such as brightness enhancement films and diffusion films, is constantly expanding. As a key consumable in the production and storage of optical films, the performance requirements for surface protective film are becoming increasingly stringent.

[0003] For example, CN116790211A discloses an adhesive resin composition and its preparation method, as well as a self-adhesive protective film. The adhesive resin composition is made by combining SEBS or SEPS with a hydrogenated styrene-farnesene block copolymer and an tackifying resin. The resulting self-adhesive protective film has high initial tack and better overall softness, which improves the adhesion of the self-adhesive protective film and can better meet the adhesion requirements of highly resilient prism sheets. At the same time, the hydrogenated styrene-farnesene block copolymer has a high molecular weight and is not easy to precipitate, so it has no effect on the processing performance of the adhesive resin composition. It can effectively improve the initial peel force of the protective film on highly resilient prism sheets, thereby avoiding paste residue and surface contamination.

[0004] Because optical thin film surfaces can have highly smooth mirror surfaces and matte surfaces with finely textured structures, separate protective films are typically designed for mirror and matte surfaces based on their characteristics. While existing technologies such as CN116790211A provide a protective film that improves adhesion, their design approach is limited to optimizing the adhesion performance of a single surface (e.g., improving the initial adhesion of prism sheets), and does not solve the industry challenge of universally bonding both matte and mirror surfaces of optical films. It can only meet the bonding protection requirements of a single side of the optical thin film. Therefore, there is an urgent need to develop a surface protective film that can simultaneously protect both matte and mirror surfaces of optical thin films. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned deficiencies of existing surface protective films and to provide an adhesive resin composition and a surface protective film. This adhesive resin composition, capable of forming a three-phase structure of "adhesive wetting phase - crosslinked network phase - nano-protrusion phase," is used as a self-adhesive layer for the surface protective film. It can autonomously respond to different surface topologies, achieving universal adhesion and protection for both matte and mirror surfaces of optical films.

[0006] A first aspect of the present invention provides an adhesive resin composition comprising a crosslinked network phase formed of a polymer, a tackifying and wetting phase formed of a fully hydrogenated petroleum resin, and a nano-protrusion phase with a transverse dimension of 50 nm to 200 nm formed at the crosslinking points of the crosslinked network phase; wherein the polymer is a hydrogenated block copolymer having physical crosslinking capability.

[0007] In the above-mentioned adhesive resin composition, the fully hydrogenated petroleum resin constitutes a continuous tackifying and wetting phase, the polymer constitutes a cross-linked network phase, and its cross-linking points constitute a nano-protrusion phase uniformly dispersed in the tackifying and wetting phase, presenting a three-phase structure of "tackifying and wetting phase - cross-linked network phase - nano-protrusion phase". Therefore, it has extremely high cohesive strength and elastic recovery force, and macroscopically exhibits a unique viscoelastic property that combines high viscosity and high elasticity, so as to autonomously respond to different surface topologies. When used as a self-adhesive layer for surface protective film, it can achieve universal bonding and protection for both matte and mirror surfaces of optical films.

[0008] In the above scheme, the lateral dimension of the nano-protrusion phase is further limited to 50nm-200nm. Here, the lateral dimension refers to the average value of the equivalent circle diameter obtained by statistically measuring the dispersed nano-protrusion phase particles through scanning electron microscopy (SEM) of the cross-section of the self-adhesive layer. Within this dimension, the above adhesive resin composition, when used as a self-adhesive layer of the surface protective film, has a sufficient number and density of protrusions to provide uniform and strong microscopic support points and mechanical engagement points. When the lateral dimension is less than 50nm, the nano-protrusion phase is too small and the density is too high, resulting in a blurred interface between it and the tackifying and wetting phase. It tends to form a homogeneous system with a moderate modulus. When used as a self-adhesive layer of the surface protective film, its initial adhesion is acceptable, but its support is poor. It lacks enough high-modulus "anchor points" to effectively support and restrict deformation. Moreover, the protrusions are too small to effectively penetrate and engage the rough peaks of the matte surface, causing the adhesive resin composition to lose its "intelligent response" ability and failing to simultaneously meet the requirements of anti-pause printing on the mirror surface and peel force on the matte surface. When the lateral dimension is greater than 200 nm, the nano-protrusion phase is too large and scarce, forming a rough microstructure. Large-sized protrusions lead to local contact stress concentration and poor overall wettability. When used as a self-adhesive layer of surface protective film, the initial adhesion is uneven, and stress is easily concentrated at the root of the protrusion, creating stress concentration points that become the starting point of damage. Physical cross-linking points are scarce, the three-dimensional network is fragile, and the cohesive strength decreases. Moreover, the large-sized protrusions themselves may become indentation sources under pressure. The overall performance is characterized by easy residue, poor resistance to printing defects, poor adhesion, and unreliable overall performance.

[0009] Preferably, the mass ratio of the polymer to the fully hydrogenated petroleum resin is 100:85-100:110. When the ratio of the polymer to the fully hydrogenated petroleum resin is within the above range, a three-phase structure of "tackifying and wetting phase - cross-linking network phase - nano-protrusion phase" can be better formed. On the one hand, this avoids the formation of a continuous tackifying and wetting phase, ensuring sufficient initial wettability and improving effective adhesion to the mirror surface; on the other hand, it allows the nano-protrusion phase formed at the cross-linking points of the polymer to have sufficient density, forming a three-dimensional physical cross-linking network sufficient to suppress plastic deformation.

[0010] The polymer and fully hydrogenated petroleum resin only need to be able to form a three-phase structure of "tackifying and wetting phase - cross-linked network phase - nano-protrusion phase", for example:

[0011] (1) The polymer is hydrogenated star-shaped SEPS, and the fully hydrogenated petroleum resin is hydrogenated C9 petroleum resin.

[0012] (2) The polymer is hydrogenated star-shaped SEBS, and the fully hydrogenated petroleum resin is hydrogenated DCPD resin.

[0013] Preferably, the styrene content (St) of the hydrogenated star-shaped SEPS or hydrogenated star-shaped SEBS is 28%-32%, and the weight-average molecular weight (Mw) is 180,000 g / mol-250,000 g / mol. The suitable styrene content ensures that the physical cross-linking points, i.e., the styrene hard segment microregions, have sufficient strength and density. A weight-average molecular weight within the above range ensures that the molecular chains have sufficient entanglement ability, thereby endowing the elastic network with excellent cohesive strength and resistance to plastic deformation.

[0014] (3) The polymer is a partially cross-linked POE and the fully hydrogenated petroleum resin is a hydrogenated terpene resin.

[0015] Preferably, the fully hydrogenated petroleum resin has a softening point of 100℃-120℃, a number-average molecular weight (Mn) <1000g / mol, and a polydispersity index (PDI) <1.8. The softening point and number-average molecular weight (Mn) of the fully hydrogenated petroleum resin within the above range ensure excellent viscosity and good wettability at room temperature; the polydispersity index (PDI) <1.8 fundamentally eliminates the formation of low molecular weight oligomer components, thereby preventing the migration of small molecules.

[0016] Preferably, the fully hydrogenated petroleum resin has a yellowing index (YI) of <5 to ensure appearance requirements.

[0017] A second aspect of the present invention provides a surface protective film comprising the above-described adhesive resin composition.

[0018] Specifically, the surface protective film comprises a substrate layer, a core layer, and a self-adhesive layer stacked sequentially, wherein the self-adhesive layer is formed from the adhesive resin composition.

[0019] The mechanism by which the above-mentioned adhesive resin composition, as a self-adhesive layer, imparts a surface protective film and achieves universal adhesion and protection is as follows:

[0020] When applying the mirror, under slight pressure, the relatively soft, high-surface-energy tackifying and wetting phase rapidly wets the surface, providing instantaneous initial adhesion through strong van der Waals forces. Simultaneously, the dispersed, high-modulus nano-protrusion phase provides solid physical support points, limiting the overall deformation depth of the tackifying and wetting phase and avoiding excessively large actual contact area. This ensures stable peel force and excellent resistance to print stoppage.

[0021] When applied to a matte surface, under pressure, the high-modulus nano-protrusion phase first contacts and locally penetrates the tips of the rough peaks on the matte surface. Simultaneously, the soft, tackifying and wetting phase encapsulating the nano-protrusion phase flows and elastically deforms, fully filling and encapsulating the contours of the rough peaks, forming a strong, recoverable mechanical interlocking structure. The nano-protrusion phase constitutes the anchor points of the interlocking, while the tackifying and wetting phase provides excellent wetting and filling properties. During peeling, the highly elastic cross-linked network phase ensures that this mechanical interlocking can be quickly and completely separated without leaving any residue.

[0022] Preferably, the storage modulus (G') of the self-adhesive layer, measured at 25°C and 1Hz, is 1.2×10^6 Pa to 2.5×10^6 Pa. When the storage modulus is below the above range, the self-adhesive layer has poor resistance to plastic deformation and cannot effectively suppress the increase of force over time and prevent stoppage marks; when the storage modulus is above the above range, the initial wettability of the self-adhesive layer is poor and instantaneous effective adhesion cannot be achieved.

[0023] Preferably, the self-adhesive layer, relative to the total amount of 100 parts of the polymer and fully hydrogenated petroleum resin mixture, further includes 0.3-0.8 parts of phenolic antioxidant, without any other additives. The phenolic antioxidant prevents thermo-oxidative degradation of the polymer during high-temperature processing and long-term use, maintaining the stability of the molecular structure. Furthermore, the absence of any additives completely eliminates the risk of migration and contamination that may arise from common small-molecule additives, achieving a non-migration-prone and highly clean protective film.

[0024] Preferably, the thickness of the self-adhesive layer is 8μm-15μm.

[0025] Preferably, the substrate layer has a longitudinal and transverse tensile modulus of elasticity >1100 MPa and a surface resistivity <10^11 Ω / sq, which is used to provide rigid support and antistatic properties.

[0026] Preferably, the surface protective film, wherein the substrate layer comprises high isotactic homopolymer polypropylene and a permanent polymeric antistatic agent, provides sufficient mechanical strength to resist external impacts and winding pressure, further preventing the formation of stop marks, and integrates permanent antistatic function to prevent dust accumulation.

[0027] Preferably, the permanent polymeric antistatic agent is a polyether block amide. This type of antistatic agent forms a conductive channel through the hydrophilic groups in the molecule, which does not migrate and can prevent pollution caused by the precipitation of small molecule antistatic agents.

[0028] Preferably, the melt flow rate (MFR) of the high isotactic homopolymer polypropylene (230°C / 2.16kg) is 6.0g / 10min-9.0g / 10min.

[0029] Preferably, the amount of the permanent polymeric antistatic agent added is 1wt%-3wt% relative to the total content of the substrate layer.

[0030] Preferably, the thickness of the substrate layer is 20μm–35μm.

[0031] Preferably, the core layer comprises polypropylene and polyethylene to improve the adhesion between the substrate layer and the self-adhesive layer.

[0032] Preferably, the core layer further comprises a permanent antistatic agent at a content of 1wt%-2wt% relative to the total content of the core layer. The permanent antistatic agent is a polyether block amide, which further enhances the antistatic properties of the protective film.

[0033] Preferably, the thickness of the core layer is 10 μm–20 μm.

[0034] A third aspect of the invention provides the application of the above-mentioned surface protective film for protecting the matte and / or mirror surfaces of optical thin films, particularly suitable for protecting both matte and mirror surfaces.

[0035] The surface protective film of the present invention can be prepared by the following method, including:

[0036] S1. Pretreatment step: Vacuum dry the polymer and fully hydrogenated petroleum resin at 60℃-70℃ for 4 hours.

[0037] S2. Preparation steps of self-adhesive layer masterbatch: The dried raw materials from step S1 and the antioxidant are poured into a high-speed mixer and premixed for 5 minutes. Then, they are melt-blended and granulated using a twin-screw extruder. The processing temperature range is strictly controlled between 170℃ and 190℃, and the screw speed is set to 300rpm-400rpm to apply high shear force and ensure the formation of a three-phase structure of "adhesive wetting phase - cross-linked network phase - nano-protrusion phase".

[0038] S3. Casting molding step: The three layers of raw materials—the substrate layer, the core layer, and the self-adhesive layer—are fed into the corresponding feeding systems of a three-layer co-extrusion casting machine. After extrusion through a T-die at 220℃-230℃, they are rapidly cooled and shaped on cooling rollers at 20℃-25℃. By implementing the above technical solution, compared with the prior art, the present invention has at least the following advantages:

[0039] 1. The adhesive resin composition provided by the present invention has extremely high cohesive strength and elastic recovery force by constructing a three-phase microstructure of "tackifying and wetting phase - cross-linking network phase - nano-protrusion phase". On a macroscopic scale, it exhibits unique viscoelastic properties that combine high viscosity and high elasticity, so as to autonomously respond to different surface topologies.

[0040] 2. The protective film provided by the present invention has a self-adhesive layer formed by the adhesive resin composition, which can respond autonomously to different surface topologies, realize universal adhesion and protection for both matte and mirror surfaces of optical films, and improve the appearance performance of the protective film through further optimization of the composition. Detailed Implementation

[0041] To make the technical solution and effects of the present invention clearer, the following detailed description is provided in conjunction with specific embodiments. It should be understood that these embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0042] In this specific embodiment, an adhesive resin composition is provided, comprising a polymer, a fully hydrogenated petroleum resin, and a phenolic antioxidant, wherein the mass ratio of the polymer to the fully hydrogenated petroleum resin is 100:85-100:110; and the amount of phenolic antioxidant added is 0.3-0.8 parts relative to 100 parts of the total mixture of polymer and fully hydrogenated petroleum resin.

[0043] The specific embodiments and comparative examples are shown in Table 1:

[0044] Table 1. Composition of specific embodiments and comparative examples

[0045]

[0046] The compositions of the above embodiments and comparative examples were prepared according to the following preparation method:

[0047] Using the above-mentioned adhesive resin compositions as self-adhesive layers, corresponding surface protective films are prepared, comprising a substrate layer, a core layer, and a self-adhesive layer stacked sequentially, wherein...

[0048] Substrate layer: It is made of 97% Daelin Kogyo SEETEC H5310 high isotactic homopolymer polypropylene (MFR (230°C / 2.16kg)=8.0g / 10min) and 3% Arkema Pebax® MH 1657 polyether block amide antistatic masterbatch, with a thickness of 25μm, longitudinal and transverse tensile modulus of elasticity (MD / TD)>1100Mpa, and surface resistivity<10^11Ω / sq.

[0049] Core layer: Contains a polypropylene / polyethylene blend, including Lotte Chemical's LOTTE H5310 polypropylene, Total Energy's LDPE 1020 low-density polyethylene, and 1-2% Arkema Pebax® MH 1657 antistatic masterbatch. Thickness is 15μm.

[0050] Self-adhesive layer: The adhesive resin compositions of the above embodiments and comparative examples are supplemented with 0.5 parts of phenolic antioxidant JADEWIN AN 1726 (SONGWON) relative to 100 parts of the total mixture of polymer and fully hydrogenated petroleum resin. The thickness is 12 μm.

[0051] Note: All percentages above are mass percentages.

[0052] The above-mentioned surface protective film is prepared according to the following method:

[0053] S1. Pretreatment step: Vacuum dry the polymer and fully hydrogenated petroleum resin at 60-70℃ for 4 hours.

[0054] S2. Preparation steps of self-adhesive layer masterbatch: The dried raw materials from step S1 and the antioxidant are poured into a high-speed mixer and premixed for 5 minutes. Then, they are melt-blended and granulated using a twin-screw extruder. The processing temperature range is strictly controlled between 170-190℃, and the screw speed is set to 300-400rpm to apply high shear force and ensure the formation of a three-phase structure of "adhesive wetting phase - cross-linked network phase - nano-protrusion phase".

[0055] S3. Casting molding step: The three layers of raw materials, namely the substrate layer, core layer and self-adhesive layer, are fed into the corresponding feeding system of the three-layer co-extrusion casting machine. After being extruded through a T-die at 220-230℃, they are rapidly cooled and shaped on a cooling roller at 20-25℃.

[0056] The surface protective film obtained above was tested for relevant properties. The testing methods are as follows, and the test results are shown in Table 2.

[0057] Detection method:

[0058] Adhesion evaluation: Differentiated initial peel force was used for characterization.

[0059] Detection method:

[0060] The test was conducted using a universal testing machine at a peeling speed of 300 mm / min and a peeling angle of 180°.

[0061] Initial peel force (Fc): The protective film was attached to a standard Clear surface optical film (Ra<0.05μm) and measured 20 minutes later.

[0062] Initial peel strength (Fm) of matte surface: The protective film is attached to a standard matte optical film (Ra=1.5μm) and measured 20 minutes later.

[0063] The relationship between evaluation criteria and mechanisms:

[0064] Good adhesion is indicated by the following criteria: 2gf / 25mm≤Fc≤7gf / 25mm and 3gf / 25mm≤Fm≤15gf / 25mm.

[0065] For mirror surfaces, the extremely low peel force range of 2-7gf / 25mm ensures that the tackifying and wetting phase can provide sufficient van der Waals force for adhesion, while the strong cross-linked network phase can effectively limit deformation, thereby absolutely avoiding print stoppage.

[0066] For matte surfaces, a moderately higher range of 3-15gf / 25mm demonstrates that the nano-protrusion phase forms an effective mechanical interlock, while the high cohesive strength within this range ensures easy peeling without residue.

[0067] 2. Time-dependent stability evaluation: The peel strength growth was characterized by a 30-day growth rate.

[0068] Detection method:

[0069] Stability at room temperature (standard conditions).

[0070] Apply the protective film to the optical thin-film mirror and the frosted surface using the method described above.

[0071] • Test conditions: 23±2℃, 50±10%RH, stored for 30 days.

[0072] • Purpose: To evaluate the basic stability of the protective film under ideal standard conditions, which is an industry benchmark test.

[0073] High temperature and high humidity accelerate aging stability (severe conditions)

[0074] After the storage period, remove the product and let it sit for 20 minutes, then test the peel strength (F) according to the above testing method. 30 )

[0075] • Test conditions: 40±2℃, 90±5%RH, stored for 7 days.

[0076] • Purpose: This is an accelerated test to assess the anti-aging ability of protective films under harsh environments. High temperature and humidity greatly accelerate the creep and aging of the colloid, exposing potential quality problems (such as adhesion growth, residue, and exudation) more quickly. Products that pass this test will have significantly improved reliability.

[0077] After the storage period, remove the product and let it sit for 20 minutes, then test the peel strength (F) according to the above testing method. l ).

[0078] Evaluation criteria:

[0079] Stability at room temperature over time: (F 30 –F 初始 ) / F初始 ×100%.

[0080] High temperature and high humidity accelerate aging stability: (F l –F 初始 ) / F 初始 ×100%

[0081] Where Finitial is the initial peel force obtained from the pass-through evaluation.

[0082] Excellent: <40%

[0083] Qualified: 40%-60%

[0084] Poor: ≥60% (usually accompanied by residual adhesive risk)

[0085] 3. Pause prints and contamination: A uniform observation method was used.

[0086] Detection method:

[0087] Stoppage / Contamination Test: The protective film is adhered to the optical thin-film mirror and cut to A4 size. It is then stored at 50°C and 20kg pressure for 14 days. After removal, the protective film is peeled off from the mirror and observed at a 20° angle under a standard light source box.

[0088] Note: Because mirrors are more likely to reveal surface contamination issues on the protected object, only mirrors are tested in this category.

[0089] Evaluation criteria:

[0090] Pass: The protected surface has no visible white spots, glue residue, hazy residue, shadows, or pause marks.

[0091] Failed: Any of the above defects occurred.

[0092] Table 2. Test results of relevant properties of surface protective films with different self-adhesive layers.

[0093]

[0094] As can be seen from the results shown in Table 2, Examples 1-4 verified the performance of compositions with different combinations of polymers and fully hydrogenated petroleum resins of various types and proportions as self-adhesive layers for protective films. All of them can achieve universal adhesion to both mirror and matte surfaces, and the peel strength and anti-stopping print performance are within a suitable range.

[0095] Examples 5-6 verified the performance of the protective film under different ratios of polymer and petroleum resin combinations. Example 5 had a high proportion of petroleum resin, which was expected to produce the best initial tack, but the cohesive strength was challenged. The results showed that its resistance to stop-marking was slightly weaker, but still within an acceptable range. Example 6 had a lower proportion of petroleum resin, which was expected to produce high cohesive strength, but the initial tack was challenged. The results showed that its mirror-like initial tack was slightly weaker, but still within the effective adhesion range.

[0096] Examples 7-8 demonstrate the protective film performance corresponding to different storage moduli. Example 7 achieves a high storage modulus for the self-adhesive layer by increasing the polymer molecular weight and styrene content, which is expected to provide good support for matte surfaces, but slightly weaker initial adhesion for mirror surfaces. Data confirms this trend, but the performance is still above "good". Example 8 achieves a lower storage modulus for the self-adhesive layer by reducing the polymer molecular weight and styrene content. Good initial adhesion for mirror surfaces is expected, but slightly weaker creep resistance. Data confirms that its resistance to stop-printing faces challenges, but remains within acceptable limits.

[0097] Example 9: Cross-system principle verification

[0098] Objective: To demonstrate that the "three-phase structure" concept of this invention is a general design principle across material systems, rather than being specific to styrene block copolymers.

[0099] Design logic: The combination of partially cross-linked POE and hydrogenated terpene resin was used. The results showed that the adhesion, peel strength stability over time, and resistance to stoppage printing were all within a suitable range.

[0100] In Comparative Example 1, the star-shaped SEPS was replaced with a linear SEPS, and all other conditions were exactly the same as in Example 1. The results showed a matte finish, high stress over time, and severe stop marks, which contrasted sharply with Example 1, demonstrating that the star-shaped structure is indispensable for high cohesive strength.

[0101] In Comparative Example 2, the fully hydrogenated C9 resin was replaced with a partially hydrogenated C9 resin, with all other conditions identical to Example 1. The results showed severe precipitate contamination and yellowing of the product, despite acceptable initial adhesion properties. This demonstrates that full hydrogenation is essential for achieving high cleanliness and appearance.

[0102] In Comparative Example 3, the mass ratio was adjusted to 100:70, which deviated significantly from the range of 100:85-100:110. The amount of resin was severely insufficient. Insufficient resin could not form a continuous tackifying and wetting phase, resulting in extremely poor initial tack and inability to achieve effective bonding.

[0103] Comparative Example 4 replicates the formulation of Example 1 in CN116790211A (containing hydrogenated styrene farnesene, etc.). This prior art represents a conventional approach to improving the adhesion of a single surface. Test results show that it cannot balance universal adhesion (especially matte residue), and its overall stability (such as high temperature and high humidity performance) and anti-fouling properties are inferior to those of this invention. This comparison directly demonstrates the significant advancement of this invention in solving the technical problem of "universal adhesion".

Claims

1. An adhesive resin composition, characterized in that, The polymer comprises a crosslinked network phase formed by a polymer, a tackifying and wetting phase formed by a fully hydrogenated petroleum resin, and a nano-protrusion phase with a transverse dimension of 50 nm-200 nm formed at the crosslinking points of the crosslinked network phase; the polymer is a hydrogenated block copolymer with physical crosslinking ability; the polymer is at least one of hydrogenated star-shaped SEPS, hydrogenated star-shaped SEBS, and partially crosslinked POE, wherein the styrene content of the hydrogenated star-shaped SEPS or hydrogenated star-shaped SEBS is 28%-32%, and the weight-average molecular weight is 180,000 g. / mol-250000g / mol; the mass ratio of the polymer to the fully hydrogenated petroleum resin is 100:85-100:110; the softening point of the fully hydrogenated petroleum resin is 100℃-120℃, the number average molecular weight is <1000g / mol, and the polydispersity index is <1.8; the yellowing index of the fully hydrogenated petroleum resin is <5; the transverse dimension refers to the average value of the equivalent circle diameter obtained by statistically measuring the dispersed nano-protruding phase particles on the cross-section of the self-adhesive layer through scanning electron microscopy.

2. A surface protective film, comprising a substrate layer, a core layer, and a self-adhesive layer stacked sequentially, characterized in that, The self-adhesive layer comprises the adhesive resin composition of claim 1.

3. The surface protective film according to claim 2, characterized in that, The energy storage modulus of the self-adhesive layer measured at 25°C and 1Hz is 1.2×10^6 Pa - 2.5×10^6 Pa.

4. The surface protective film according to claim 2, characterized in that, The self-adhesive layer, relative to the total amount of 100 parts of the mixture of polymer and fully hydrogenated petroleum resin, also includes 0.3 to 0.8 parts of phenolic antioxidant.

5. A surface protective film according to claim 2, characterized in that, The thickness of the self-adhesive layer is 8μm-15μm.

6. The application of the surface protective film as described in any one of claims 2-5, characterized in that, Used to protect the matte and / or mirror surfaces of optical films.

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