An adhesive and an easily vented protective film thereof, and a method for preparing the easily vented protective film.

Abstract

This invention provides an adhesive whose raw materials include: acrylate adhesive, isocyanate curing agent, and organometallic catalyst. The organometallic catalyst is selected from at least one of organotin catalyst, organozirconium catalyst, and organobismuth catalyst. The ratio of acrylate adhesive, isocyanate curing agent, and organometallic catalyst satisfies N(OH-):N(NCO-):N(Me)=8:4:0.5~1.2, where N(OH-) represents the amount of hydroxyl groups in the acrylate adhesive, N(NCO-) represents the amount of isocyanate groups in the isocyanate curing agent, and N(Me) represents the amount of metal element in the organometallic catalyst. This adhesive has a fast curing speed, completing curing before leveling and collapse, and the resulting adhesive layer has high bonding strength.

Description

Technical Field

[0001] This invention belongs to the field of protective films, specifically relating to an adhesive and an easily vented protective film using the same, and a method for preparing the easily vented protective film. Background Technology

[0002] Applying protective films is a common protective measure on the market, as the demand for surface protection of 3C products has been increasing in recent years. The air release performance and adhesion performance of the protective film directly affect the appearance and safety of the product. If the adhesive force of the protective film is insufficient, it is easy for the protective film to loosen and slip off during use.

[0003] However, during the application of protective film, air can easily get trapped between the film and the substrate, leaving air bubbles on the bonding surface and resulting in an uneven surface. Commercially available protective films often use glue dots arranged in a spaced-out pattern to remove air bubbles. However, the curing time for these glue dots is typically 3 days or more. This excessive curing time can cause the glue dots to deform under pressure, blocking the intended air vents and defeating the purpose of the dotted adhesive. Protective films made with these dotted glue dots still tend to have high wrinkles and fail to achieve a smooth surface.

[0004] Therefore, it is necessary to find an adhesive that can cure quickly and produce adhesive layers with high bonding strength to meet consumer demand. Summary of the Invention

[0005] The purpose of this invention is to provide an adhesive and an easy-venting protective film using the same, as well as a method for preparing the easy-venting protective film. The adhesive has a fast curing speed and the adhesive layer obtained has high bonding strength. The easy-venting protective film prepared using this adhesive can ensure strong adhesion, good venting effect, meet the appearance requirements of a flat surface after bonding, and is not easy to warp.

[0006] According to a first aspect of the present invention, an adhesive is provided, the raw materials of which include the following materials: acrylate adhesive, isocyanate curing agent, and organometallic catalyst, wherein the organometallic catalyst is selected from at least one of organotin catalyst, organozirconium catalyst, and organobismuth catalyst; the ratio of acrylate adhesive, isocyanate curing agent and organometallic catalyst satisfies N(OH-):N(NCO-):N(Me) = 8:4:0.5~1.2, wherein N(OH-) represents the amount of hydroxyl groups in the acrylate adhesive, N(NCO-) represents the amount of isocyanate groups in the isocyanate curing agent, and N(Me) represents the amount of metal elements in the organometallic catalyst.

[0007] This adhesive has a rapid curing speed, completing curing before leveling, and produces a high-strength adhesive layer. The curing rate of the adhesive is related to the concentration of hydroxyl and isocyanate groups in the adhesive; the higher the reactant concentration, the shorter the required curing time at the same curing temperature. Simultaneously, to ensure a reasonable curing time, a catalyst is needed. The organometallic catalyst selected in this invention first combines with the isocyanate groups to form an intermediate complex, then reacts with the hydroxyl groups. After the reaction, the organometallic catalyst reverts to its original state, restoring its reactivity and allowing it to participate in the reaction again. When the raw materials of the adhesive meet the above-mentioned proportions, the concentrations of hydroxyl and isocyanate groups ensure that the reaction can proceed and the desired cured product is obtained. The organometallic catalyst can lower the activation energy of the reaction and accelerate the reaction. Moreover, compared with organolead, organomercury, and other organometallic catalysts, organotin, organozirconium, and organobismuth not only have higher catalytic activity for the reaction between isocyanate and hydroxyl groups but are also non-toxic and environmentally friendly.

[0008] Preferably, the organometallic catalyst includes at least one of alkoxides and chelates. Such catalysts exhibit better selectivity for isocyanate / hydroxyl groups, reduce isocyanate side reactions, and efficiently promote isocyanate / hydroxyl reactions under different aging conditions; furthermore, they possess excellent catalytic stability, maintaining considerable catalytic capacity in repeated experiments and production.

[0009] Preferably, the acrylic adhesive is obtained by polymerization of monomers, including at least one of hydroxyethyl acrylate, acrylic acid, and methyl acrylate. Using these materials as monomers not only ensures that the acrylic adhesive provides a suitable range of hydroxyl concentrations for the adhesive, but also results in adhesives with high strength, impact resistance, and excellent weather resistance.

[0010] Preferably, the raw materials of acrylate adhesives also include an initiator.

[0011] Preferably, the initiator is selected from at least one of azobisisobutyronitrile (AIBN) and ethyl isocyanate acrylate.

[0012] Preferably, the raw materials for acrylate adhesives also include monomer solvents.

[0013] Preferably, the monomer solvent includes ethyl acetate.

[0014] Preferably, by weight, the raw materials for the acrylic adhesive include: 3-5 parts hydroxyethyl acrylate, 1-3 parts acrylic acid, 30-60 parts methyl acrylate, 60-70 parts ethyl acetate, 0.4-1.0 parts azobisisobutyronitrile, and 1-10 parts ethyl isocyanate acrylate. The acrylic adhesive prepared from the above materials, when used as a raw material for an adhesive, enables the resulting adhesive layer to possess excellent bonding properties and stronger adhesion. This ensures that the adhesive layer effectively performs its bonding function and prevents the adhered object from detaching due to insufficient adhesion during use and drops.

[0015] Preferably, the weight-average molecular weight of the acrylic adhesive is 200,000 to 400,000.

[0016] Preferably, the isocyanate curing agent is a diisocyanate.

[0017] Preferably, the isocyanate curing agent is selected from at least one of diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, 2,4-methylcyclohexane diisocyanate, and 2,6-methylcyclohexane diisocyanate.

[0018] Preferably, the adhesive raw materials include 90-100 parts of acrylic adhesive, 1.0-1.5 parts of curing agent, 0.06-0.15 parts of catalyst, and 20-40 parts of solvent by mass.

[0019] Furthermore, the catalysis of hydroxyl and isocyanate groups by organometallic catalysts can be adjusted according to production needs. In this system, if the concentration of hydroxyl and isocyanate groups remains constant and the catalyst ratio is lower than the above ratio, the curing time of the adhesive is not significantly reduced; if the catalyst ratio is higher than the above ratio, the hydroxyl and isocyanate groups react too quickly, resulting in skin formation or even glue coagulation on the adhesive surface, which is not conducive to actual production.

[0020] Preferably, the adhesive raw materials also include an inhibitor, which is a saturated fatty acid, with an inhibitor-to-organometallic catalyst ratio of 1:0.06-0.15 by weight. The inhibitor is added to the system to suppress the organometallic catalyst, preventing it from promoting the reaction between isocyanate groups and hydroxyl groups before coating, thus avoiding skinning and coagulation of the adhesive before actual production. Saturated fatty acids are chosen as inhibitors because they effectively inhibit the catalytic effect of the organometallic catalyst on isocyanate / hydroxyl groups, and because saturated fatty acids have low boiling points, allowing the inhibitor to volatilize during actual production, enabling the organometallic catalyst in the system to quickly exert its catalytic effect. Adjusting the inhibitor dosage according to this ratio maintains the adhesive system in an uncatalyzed state before coating, and the inhibitor dosage within this range is easily volatilized during actual production, thus detaching from the adhesive system.

[0021] Preferably, the raw materials of the adhesive also include a solvent.

[0022] Preferably, the solvent is selected from at least one of ethyl acetate, butyl acetate, dimethyl carbonate, butanone, toluene, and xylene. Using the above materials as solvents can effectively dissolve acrylate adhesives, isocyanate curing agents, and organometallic catalysts in a single system, promoting group reactions.

[0023] Preferably, the solvent includes ethyl acetate. Since ethyl acetate is also present in acrylic adhesives, which constitute a large proportion of adhesive raw materials, using ethyl acetate as a solvent makes it easier to dissolve all the adhesive raw materials in the solvent.

[0024] According to a second aspect of the present invention, an easily vented protective film is provided, comprising an adhesive layer and a substrate layer for supporting the adhesive layer. The adhesive layer is composed of a plurality of spaced-apart adhesive units; the adhesive units are made of the aforementioned adhesive. This easily vented protective film designs the adhesive layer as spaced-apart adhesive units. The adhesive units ensure sufficient adhesion after the adhesive layer is bonded, and the spacing between the adhesive units also serves as venting channels to allow gas to escape, thereby solving the problem of bulging after the easily vented protective film is bonded.

[0025] Preferably, the shape of a single adhesive unit is at least one of rhombus, circle, and square.

[0026] Preferably, the shape of a single adhesive unit is square.

[0027] Preferably, the gap between adjacent adhesive units serves as the venting channel for the easily vented protective film, with the width of the venting channel as X and the thickness of the adhesive unit as H, where H / X = 0.004 to 0.006. An easily vented protective film within this range ensures that the adhesive layer contains venting pathways, allowing air to escape during bonding, preventing bulging and improving the appearance and safety of the bonded object. It also ensures that the adhesive layer with venting channels is sufficiently secure to the bonded object, preventing loosening during drops and improving its drop resistance. If the adhesive unit is too thin and the venting channel is too wide, the adhesive strength is insufficient to protect the bonded object; if the adhesive unit is too thick and the venting channel is too narrow, the required curing time for the adhesive layer is too long, and incompletely cured adhesive can easily flow into the venting channel, causing the adhesive layer to collapse and the reserved venting channel to be blocked, thus failing to achieve the desired venting effect.

[0028] Preferably, the thickness H of the adhesive unit is 12–20 μm.

[0029] Preferably, the thickness of the substrate layer is 30–50 μm.

[0030] According to a third aspect of the present invention, a method for preparing an easily vented protective film is provided. An adhesive is applied at intervals to the surface of a substrate layer to form a plurality of mutually spaced adhesive regions on the surface of the substrate layer. The adhesive in the adhesive regions is then cured at 50–70°C for 1–3 hours to obtain a molded adhesive unit. Using the above-mentioned adhesive as the adhesive layer of the easily vented protective film ensures that the adhesive completes curing before collapse during the curing process, maintaining the venting channels unobstructed by the adhesive, allowing the easily vented protective film to vent smoothly and maintain a flat appearance after bonding. Under these curing conditions, the adhesive can be fully cured. If the curing temperature is too low, the required curing time increases, the probability of adhesive collapse increases, and the venting channels may become smaller, failing to achieve the expected venting effect. If the temperature is too high, although the required curing time decreases, wrinkles easily appear on the surface of the adhesive unit, and the curing cost increases, which is detrimental to actual production.

[0031] Preferably, before the adhesive is cured, it needs to be dried at a temperature of 60–120°C, gradually increasing from 60°C to 120°C and then decreasing to 60°C. Within this temperature range, the inhibitor can be rapidly volatilized, while other raw materials are not volatilized and remain in the adhesive system. The organometallic catalyst in the system rapidly catalyzes the curing reaction of the adhesive, achieving the purpose of rapid curing.

[0032] Preferably, the coating speed is 25–30 m / min.

[0033] Preferably, the surface of the substrate layer is subjected to corona treatment. Corona treatment can increase the surface energy of the substrate layer, which can increase the adhesion between the substrate layer and the adhesive layer, making it easier for the adhesive to be bonded after being applied to the substrate layer, and maintaining the discontinuous shape of the adhesive unit spacing. Attached Figure Description

[0034] Figure 1 A schematic diagram of the surface for easy-to-vent protective film adhesion;

[0035] Figure 2 A schematic diagram of the cross-section of the easily vented protective membrane;

[0036] The corresponding relationships of the reference numerals in the attached figures are as follows: 1. Adhesive unit, 2. Substrate layer, X. Width of the venting channel. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] Example 1

[0039] Experimental group 1-1

[0040] The raw material formulations used in this experimental group to prepare acrylate adhesives are shown in Table 1; the raw material formulations used to prepare adhesives are shown in Table 2. The ratio of N(OH-):N(NCO-):N(Me) is 8:4:1. Here, N(OH-) represents the amount of hydroxyl groups in the acrylate adhesive, N(NCO-) represents the amount of isocyanate groups in the isocyanate curing agent, and N(Me) represents the amount of metal elements in the organometallic catalyst.

[0041] Prepare the adhesive according to the raw material formula of the adhesive and acrylic glue used in this experimental group, and prepare the adhesive according to the following steps:

[0042] The raw materials for preparing acrylic adhesive were mixed evenly and subjected to a polymerization reaction at a temperature of 70°C for 8 hours to obtain acrylic adhesive. The obtained acrylic adhesive, isocyanate curing agent, organometallic catalyst, inhibitor, and solvent were added to a reaction vessel and stirred for 15 minutes while maintaining the temperature at 23°C until homogeneous, thus obtaining the adhesive.

[0043] Table 1. Raw material formulation for preparing acrylic adhesives

[0044]

[0045] Table 2. Raw material formulation for preparing adhesives

[0046]

[0047] Experimental group 1-2

[0048] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is the amount of organometallic catalyst added in the raw materials for preparing adhesives. This results in the N(OH-):N(NCO-):N(Me) ratio of 8:4:0.5 in the raw materials of the adhesives in this experimental group, specifically by adding 0.06 parts of organometallic catalyst. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0049] Experimental groups 1-3

[0050] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is the amount of organometallic catalyst added in the raw materials for preparing adhesives. This results in the N(OH-):N(NCO-):N(Me) ratio of 8:4:1.2 in the raw materials of the adhesives in this experimental group. Specifically, 0.15 parts of organometallic catalyst were added. The other raw materials and preparation methods were strictly consistent with those of Experimental Group 1-1.

[0051] Comparison Group 1

[0052] This comparative group prepared the adhesive according to the method provided in Experimental Group 1-1. The difference between this comparative group and Experimental Group 1-1 is the amount of organometallic catalyst added in the raw materials for preparing the adhesive. This results in the N(OH-):N(NCO-):N(Me) ratio of 8:4:0.25 in the raw materials of the adhesive in this comparative group, specifically by adding 0.03 parts of organometallic catalyst. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0053] Comparison Group 2

[0054] This comparative group prepared the adhesive according to the method provided in Experimental Group 1-1. The difference between this comparative group and Experimental Group 1-1 lies in the amount of organometallic catalyst added in the raw materials for preparing the adhesive. Specifically, in this comparative group, the N(OH-):N(NCO-):N(Me) ratio in the raw materials of the adhesive is 8:4:1.6, and 0.20 parts of organometallic catalyst are added. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0055] Experimental groups 1-4

[0056] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is that the organometallic catalyst in the raw materials for preparing adhesives is different. Specifically, this experimental group used stannous octoate. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0057] Comparison Group 3

[0058] This comparative group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this comparative group and Experimental Group 1-1 is that the catalyst used in the preparation of adhesives is not an organometallic catalyst. Specifically, this comparative group used triethylenediamine as the catalyst. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0059] Experimental groups 1-5

[0060] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is that the raw materials used to prepare the adhesives do not include inhibitors. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0061] Experimental groups 1-6

[0062] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is that the polymer monomers in the raw materials for preparing acrylic adhesives only contain hydroxyethyl acrylate and methyl acrylate, specifically 6 parts of hydroxyethyl acrylate and 45 parts of methyl acrylate. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0063] Experimental groups 1-7

[0064] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is that the polymer monomers in the raw materials for preparing acrylate adhesives only contain acrylic acid and methyl acrylate, specifically 6 parts acrylic acid and 45 parts methyl acrylate. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0065] Experimental groups 1-8

[0066] This experimental group prepared adhesives according to the method provided in Experimental Group 1-1. The difference between this experimental group and Experimental Group 1-1 is that the polymer monomers in the raw materials for preparing acrylate adhesives only contain hydroxyethyl acrylate and acrylic acid, specifically 49 parts of hydroxyethyl acrylate and 2 parts of acrylic acid. The other raw materials and preparation methods are strictly consistent with those of Experimental Group 1-1.

[0067] Test Example 1

[0068] Test subjects: The test subjects in this test example are the adhesive prepared in Example 1 and a commercially available adhesive, specifically the adhesive with the brand name HS-6503 produced by Guangzhou Huisheng Technology New Materials Co., Ltd.

[0069] Test method:

[0070] The adhesive was applied to the test plate at 110℃ and dried at a temperature of 60-120℃, gradually increasing from 60℃ to 120℃ and then decreasing to 60℃. Finally, it was cured at 60℃ for different times to obtain the adhesive layer. In accordance with GB / T124-2008, shear strength test specimens (bonded surface length of 12.5mm ± 0.25mm, adhesive layer thickness of 20μm) were prepared using the cured test objects. The test objects were cured under different temperature conditions, and the shear strength of the test specimens was evaluated after the test objects were cured.

[0071] Test results:

[0072] The variables involved in the test subjects in this test case are shown in Table 3, and the test results are shown in Table 4.

[0073] According to the test results in Table 4, under the same curing temperature and curing time, the shear strength of the adhesive layers produced by the adhesives in experimental groups 1-1 to 1-5 is higher than that of control groups 1-3 and commercially available adhesives, indicating that the adhesives in experimental groups 1-1 to 1-5 require a shorter curing time. Among them, the adhesive in experimental group 1-1 has the fastest curing speed, reaching a high shear strength after only 2 hours of curing, indicating that the adhesive in experimental group 1-1 only needs to be cured completely at 60℃ for 2 hours. In contrast, commercially available adhesives require 72 hours of curing at 60℃ to reach a shear strength suitable for daily use.

[0074] Comparing the test data of experimental groups 1-1 to 1-3 and control groups 1 and 2 in Table 4, under the same curing conditions, the shear strength of the adhesive layer prepared by the adhesives of experimental groups 1-1 to 1-3 is higher than that of control group 1. This indicates that the content of the organometallic catalyst added in control group 1 is too small, and the required curing time of the adhesive is not significantly reduced. Control group 2, on the other hand, contains a larger content of organometallic catalyst. Before the isocyanate groups are saturated, the more catalyst added, the faster the catalytic rate and the shorter the curing time. However, the surface of the resulting adhesive layer develops a skin or even glue coagulation. When testing the shear strength, the gel or skin will cause the test result to be slightly higher. Furthermore, the adhesive layer prepared by control group 2 is not conducive to coating and bonding in practical applications. Therefore, when the N(OH-):N(NCO-):N(Me) ratio in the raw materials of the adhesive is 8:4:0.5–1.2, the curing speed of the resulting adhesive is fast enough, and the surface of the resulting adhesive layer is smooth and easy to use.

[0075] Comparing the shear strength of the adhesive layers obtained from experimental groups 1-1, 1-4, and control group 3, it can be seen that the shear strength of the adhesive layer obtained from control group 3 is lower at all curing times. This indicates that using an organometallic catalyst in the adhesive raw material can improve the curing rate and reduce the required curing time compared to using other catalysts. When the organometallic catalyst is selected from at least one alkoxide and / or chelate compound of tin, zirconium, and bismuth, it exhibits high catalytic stability and maintains excellent catalytic activity in multiple experiments. Comparing the test data of experimental groups 1-1 and 1-5 in Table 4, it can be seen that since no inhibitor was added to the adhesive in experimental groups 1-5, the adhesive had already started reacting at room temperature before curing. The hydroxyl and isocyanate groups reacted too quickly, resulting in skinning and coagulation of the adhesive before curing. The higher shear strength in experimental groups 1-5 is due to the formation of a skin or even glue coagulation on the adhesive surface, similar to the situation in control group 2. This is also detrimental to coating and bonding during production in practical applications.

[0076] Comparing the test data of experimental groups 1-1 and 1-6 to 1-8 in Table 4, it can be found that the shear strength of the easily vented protective film prepared in experimental group 1-1 after curing is higher than that of experimental groups 1-6 to 1-8. This indicates that when hydroxyethyl acrylate, acrylic acid, and methyl acrylate are selected as the polymerizing monomers in acrylic adhesives for polymerization, it is better than using any two of them together, achieving the effects of short curing time, low curing temperature, and high adhesion after curing.

[0077] Table 3. Variables involved in the test subjects in this test case

[0078]

[0079] Table 4. Statistical results of the familiarization status of the test subjects in Test Example 1

[0080]

[0081]

[0082] Example 2

[0083] Experimental group 2-1

[0084] This experimental group used the acrylic adhesive and bonding agent prepared in Experiment 1-1. The substrate layer 2 was made of polyethylene terephthalate film. An easily vented protective film was prepared according to the following steps:

[0085] The surface of substrate layer 2 is corona treated, and adhesive is applied to substrate layer 2 at intervals using a micro-grooved roller with a textured surface. Multiple spaced adhesive regions are formed on the corona-treated surface of substrate layer 2, resulting in a first film. The first film is then dried in an oven at a temperature of 60–120°C, gradually increasing from 60°C to 120°C and then decreasing back to 60°C to allow the inhibitors in the adhesive to evaporate, resulting in a second film. The second film is then cured at 60°C for 2 hours to obtain an easily vented protective film. The micro-grooved roller has a square texture with a depth of 2 mm, a coating speed of 25 m / min, and a drying temperature of 110°C.

[0086] The easily vented protective membrane structure obtained in this experimental group is as follows: Figure 1 and Figure 2 As shown, a plurality of spaced adhesive units 1 are provided on the surface of the substrate layer 2, and the adhesive units 1 protrude relative to the surface of the substrate layer 2. In the easily vented protective film prepared in this embodiment, the shape of a single adhesive unit 1 is square, and the space between adjacent adhesive units 1 is used as the venting channel of the easily vented protective film. The width X of the venting channel is 3 mm, the thickness H of the adhesive unit 1 is 15 μm, and the thickness of the substrate layer 2 is 40 μm.

[0087] Experimental group 2-2

[0088] This experimental group, referring to the method for preparing easily vented protective films provided in Experimental Group 2-1, prepared an easily vented protective film. The difference between this experimental group and Experimental Group 2-1 lies in the width X of the venting channel in the prepared easily vented protective film being 5 mm and the thickness H of the adhesive unit 1 being 20 μm. Specifically, the shape of the micro-concave roller texture and the coating speed were changed in the preparation method. All other raw materials, preparation methods, and process parameters remained strictly consistent with those of Experimental Group 2-1.

[0089] Experimental group 2-3

[0090] This experimental group, referring to the method for preparing easily vented protective films provided in Experimental Group 2-1, prepared an easily vented protective film. The difference between this experimental group and Experimental Group 2-1 lies in the width X of the venting channel being 2 mm and the thickness H of the adhesive unit 1 being 12 μm. Specifically, the shape of the micro-grooved roller texture and the coating speed were changed in the preparation method. All other raw materials, preparation methods, and process parameters remained strictly consistent with those of Experimental Group 2-1.

[0091] Experimental groups 2-4

[0092] This experimental group, referring to the method for preparing easily vented protective films provided in Experimental Group 2-1, prepared an easily vented protective film. The difference between this experimental group and Experimental Group 2-1 lies in the width X of the venting channel being 5 mm and the thickness H of the adhesive unit 1 being 10 μm. Specifically, the shape of the micro-grooved roller texture and the coating speed were changed in the preparation method. All other raw materials, preparation methods, and process parameters remained strictly consistent with those of Experimental Group 2-1.

[0093] Experimental groups 2-5

[0094] This experimental group, referring to the method for preparing easily vented protective films provided in Experimental Group 2-1, prepared an easily vented protective film. The difference between this experimental group and Experimental Group 2-1 lies in the width X of the venting channel being 2 mm and the thickness H of the adhesive unit 1 being 30 μm. Specifically, the shape of the micro-grooved roller texture and the coating speed were changed in the preparation method. All other raw materials, preparation methods, and process parameters remained strictly consistent with those of Experimental Group 2-1.

[0095] Comparison Group 4

[0096] This comparative group prepared an easily vented protective film using the method provided in Experimental Group 2-1. The difference between this comparative group and Experimental Group 2-1 is that the adhesive layer in the prepared easily vented protective film is a continuous adhesive layer, specifically applied using a coating roller without a textured surface. All other raw materials, preparation methods, and process parameters remained strictly consistent with Experimental Group 2-1.

[0097] Comparison Group 5

[0098] This comparative group prepared an easily vented protective film using the method provided in Experimental Group 2-1. The difference between this comparative group and Experimental Group 2-1 is the use of a commercially available adhesive, specifically HS-6503 produced by Guangzhou Huisheng Technology New Materials Co., Ltd. All other raw materials, preparation methods, and process parameters remained strictly consistent with Experimental Group 2-1, ensuring that X, Y, H1, and H2 in the prepared easily vented protective film were identical to those in Experimental Group 2-1.

[0099] Test Example 2

[0100] Test subject: The test subject in this test case is the easily vented protective film prepared in Example 2.

[0101] Test method:

[0102] (1) Peel strength test: The test method is in accordance with GB / T 2792-2014. Under the experimental conditions of peel angle of 90°, separation rate of (5.0±0.2)mm / s, ambient temperature of (23±1)℃ and relative humidity of (50±5)%, the peel strength of the easy-to-vent protective film is measured.

[0103] (2) Flatness test: The prepared easy-to-vent protective film was wrapped around the surface of 100 aluminum shells and the number of aluminum shells with uneven surfaces was recorded. The aluminum shells were cuboids with a length of 15cm, a width of 8cm and a height of 5cm.

[0104] Test results:

[0105] The product dimensions and structure of the test subjects are shown in Table 5, and the product dimension calculation results and performance test results of the test subjects are shown in Table 6.

[0106] According to the test results in Table 6, comparing the protective films prepared in experimental groups 2-1 to 2-5 with the easily vented protective film prepared in control group 4, it can be concluded that the unevenness rate in the corresponding test data of experimental groups 2-1 to 2-5 is lower, while the unevenness rate in the corresponding test data of control group 4 is higher. This indicates that the easily vented protective film of the present invention designs the adhesive layer as spaced adhesive units 1. The adhesive units 1 ensure sufficient adhesion after the adhesive layer is bonded, and the intervals between the adhesive units 1 serve as venting channels to meet the gas emission requirements, thereby solving the bulging problem after the easily vented protective film is bonded. Similarly, comparing the protective films prepared in experimental groups 2-1 to 2-5 with the protective film prepared in control group 5, it can be seen that control group 5 uses commercially available adhesives to prepare the same structured adhesive layer as experimental group 2-1, but the peel strength and unevenness rate of control group 5 are worse than those of experimental group 2-1. The experimental groups 2-1 to 2-5 use the adhesive provided by this invention as the adhesive layer for the easily vented protective film. During the curing process of the easily vented protective film, curing is ensured to be completed before the adhesive flows into the venting channels, maintaining the venting channels from being occupied by the adhesive, allowing the easily vented protective film to vent smoothly, and maintaining a flat appearance after bonding. Among the test objects in this test example, experimental group 2-1 showed the best overall bonding performance and venting performance.

[0107] Comparing the test data of the easily vented protective films prepared in experimental groups 2-1 to 2-5 in Table 6, it can be seen that the easily vented protective films in experimental groups 2-1 to 2-3 maintained both high adhesive strength and low unevenness. This indicates that when the H / X ratio in the easily vented protective film is within the range of 0.004 to 0.006, the adhesive layer forms a venting channel, allowing the air to be released during bonding, thus preventing bulging and improving the appearance and safety of the bonded object. Furthermore, it ensures that the adhesive layer with venting channels is sufficiently secure to the bonded object, preventing loosening during drops and improving its drop resistance. The peel strength of the easily vented protective film prepared in experimental groups 2-4 is relatively small, indicating that when the adhesive unit 1 is too thin and the width of the venting channel is too large, the adhesive strength of the easily vented protective film is insufficient to protect the bonded object. The unevenness rate of the easily vented protective film prepared in experimental groups 2-5 is relatively high, indicating that the adhesive unit 1 is too thick and the width of the venting channel is too small. The curing time required for the adhesive to cure into the adhesive unit 1 is too long. The incompletely cured adhesive is easy to encroach on the venting channel under the action of gravity, resulting in the reserved venting channel being filled, which further leads to a high unevenness rate and poor venting effect.

[0108] Table 5. Product Dimensions and Structures of the Test Subjects in this Test Case

[0109] Group X(mm) H(μm) Experimental group 2-1 3 15 Experimental group 2-2 5 20 Experimental group 2-3 2 12 Experimental groups 2-4 5 10 Experimental groups 2-5 2 30 Comparison Group 4 / 15 Comparison Group 5 (commercially available adhesives) 3 15

[0110] Table 6. Product dimension calculation results and performance test results of the test subjects in this test case.

[0111]

[0112] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An easily vented protective film, characterized in that, It includes an adhesive layer and a substrate layer for supporting the adhesive layer. The adhesive layer is composed of a plurality of spaced adhesive units. The spaced area between adjacent adhesive units serves as the venting channel of the easily vented protective film. The width of the venting channel is X, and the thickness of the adhesive unit is H, where H / X = 0.004~0.

006. The adhesive unit is made of an adhesive; the raw materials of the adhesive include the following materials: acrylate adhesive, isocyanate curing agent, and organometallic catalyst, wherein the organometallic catalyst is selected from at least one of organotin catalyst, organozirconium catalyst, and organobismuth catalyst; The ratio of the acrylate adhesive, the isocyanate curing agent, and the organometallic catalyst satisfies the following condition: N(OH-):N(NCO-):N(Me) = 8:4:0.5~1.2, where N(OH-) represents the amount of hydroxyl groups in the acrylate adhesive, N(NCO-) represents the amount of isocyanate groups in the isocyanate curing agent, and N(Me) represents the amount of metal elements in the organometallic catalyst.

2. The easily vented protective film as described in claim 1, characterized in that, The organometallic catalyst includes at least one of alkoxides and chelates.

3. The easily vented protective film as described in claim 1, characterized in that, The acrylate adhesive is a product obtained by polymerizing monomers through a polymerization reaction, and the polymerizing monomers include at least one of hydroxyethyl acrylate, acrylic acid, and methyl acrylate.

4. The easily vented protective film as described in claim 3, characterized in that, The polymerization reaction is carried out at 60~90℃ for 7~9 h.

5. The easily vented protective film as described in claim 3, characterized in that, The isocyanate curing agent is selected from at least one of diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, 2,4-methylcyclohexane diisocyanate, and 2,6-methylcyclohexane diisocyanate.

6. The easily vented protective film as described in claim 5, characterized in that, The adhesive comprises, by weight, 90-110 parts of acrylate adhesive, 1.0-1.5 parts of isocyanate curing agent, 0.06-0.15 parts of organometallic catalyst, and 20-40 parts of solvent.

7. The easily vented protective film as described in claim 1, characterized in that, The adhesive raw materials also include inhibitors, which include saturated fatty acids, and the ratio of the inhibitor to the organometallic catalyst is 1:0.06~0.15 by mass.

8. The method for preparing the easily vented protective film according to any one of claims 1 to 7, characterized in that, Includes the following operations: The adhesive is applied at intervals on the surface of the substrate layer to form a plurality of mutually spaced adhesive regions on the surface of the substrate layer. The adhesive in the adhesive regions is then cured at 50~70°C for 1~3 hours to obtain the molded adhesive unit.

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