A substrate-free foam tape and a substrate-free composite tape

Abstract

The present disclosure provides a substrate-free foam tape and a substrate-free composite tape. The present disclosure relates to the technical field of foam tapes. A substrate-free foam tape includes a mesh release film, an adhesive layer, and a foam layer that are sequentially stacked from bottom to top; wherein, the foam layer has adhesiveness, and the foam layer is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5 to 50 parts of elastic particles, 0.35 to 1 part of a curing agent, and 0.3 part of a black paste. In the present disclosure, after mixing the acrylic base material and the elastic particles in a certain proportion, the prepared foam layer has adhesiveness, has good adhesion to the adherend layer, and at the same time can make the modulus of the foam layer meet the requirements, so that the foam layer and the entire foam tape have good impact resistance and anti-film printing effect.

Description

Technical Field

[0001] The present disclosure relates to the technical field of foam tapes, and particularly to a substrate-free foam tape and a substrate-free composite tape. Background Art

[0002] Currently, the foam tapes on the market have a stacked structure, which generally includes a grid release film, a pressure-sensitive adhesive layer, a PET printed black film layer, a foam layer (non-adhesive), and a black anti-sticking coating. Such foam tapes are relatively thick. Another example is an OLED ultra-fine grid polypropylene foam tape disclosed in a Chinese patent application (CN221971490U), which includes: a grid light release film layer, an adhesive layer, a substrate layer, and a polypropylene foam layer. The grid light release film layer, the adhesive layer, the substrate layer, and the polypropylene foam layer are stacked in sequence from top to bottom. The grid light release film layer is a polyethylene terephthalate film layer, the adhesive layer is a modified polyacrylate pressure-sensitive adhesive layer, the substrate layer is a black antistatic printed film layer, and the polypropylene foam layer is a black closed-cell polypropylene foam layer. In addition to the necessary grid release film, pressure-sensitive adhesive, and foam layer, such foam tapes also have additional layer structures, resulting in relatively thick foam tapes.

[0003] Foam tapes are widely used in electronic devices, such as mobile phones and laptop computers. Taking mobile phones as an example, the fixed curved screen of a mobile phone generally includes, arranged from top to bottom, a CG layer (glass cover plate), a functional layer (such as POL, BP, etc.), an integral foam tape layer, and a copper foil tape layer. The copper foil tape layer includes an acrylic adhesive layer and a copper foil layer. Structurally, the integral foam tape layer connects the functional layer and the copper foil tape layer, and the copper foil tape layer realizes bonding and fixing with the integral foam tape layer by means of its own acrylic adhesive layer.

[0004] In response to the demand of the market trend of thinner mobile phones, it is required that the foam tape can be thinned on the basis of meeting the requirements of impact resistance and other related performance requirements. However, the current design of the existing integral foam tape cannot take into account both thickness and impact resistance at the same time. When the thickness is thinned, the impact resistance will decrease significantly. In addition, the modulus of the existing integral foam tape is too large, resulting in indentations after being pressed, and these indentations will affect the display effect of the mobile phone screen. Therefore, the problem of screen imprinting caused by the too large modulus of the integral foam tape is a common problem of the existing integral foam tapes on the market.

[0005] In addition, the preparation methods of the grid release films on the existing market generally include first melting PE particles, then coating the film on the surface of the substrate, embossing, and cooling to form a grid layer on the surface of the substrate, and then coating a release agent on the surface of the grid layer to form a release layer on the grid layer. For example, a kind of embossed release film disclosed in Chinese Patent Application (CN 106273956A) includes a substrate layer, a coated film layer, and a release layer; the coated film layer is arranged on the substrate layer, and the surface of the coated film layer is formed with textures; the release layer is arranged on the coated film layer and is matched and adhered to the textures. The coated film layer is a polyethylene layer or a polypropylene layer.

[0006] This grid layer / coated film layer prepared from PE material (with a maximum heat resistance of 90 °C) is not resistant to high temperatures. When the grid release film and a pressure-sensitive adhesive are used to prepare a foam tape, since the general drying temperature of the adhesive is above 100 °C, when the pressure-sensitive adhesive is coated on the release layer and dried, the grid embossing on the surface of the release film will be deformed, resulting in uneven depths of the grid-shaped exhaust grooves formed on the pressure-sensitive adhesive. Therefore, when the pressure-sensitive adhesive is adhered to the surface of the object to be pasted, the bubbles in the exhaust grooves cannot be discharged, and the exhaust grooves cannot disappear within the preset time. This not only affects the production rhythm, but also affects the appearance and performance of the object to be pasted, and in addition, equipment needs to be configured separately to eliminate the bubbles, which undoubtedly increases the production cost and production efficiency. Summary of the Invention

[0007] The present disclosure provides a substrate-free foam tape and a substrate-free composite tape to at least solve one of the technical problems existing in the prior art.

[0008] According to a first aspect of the present disclosure, there is provided a substrate-free foam tape, including a grid release film, an adhesive layer, and a foam layer which are stacked in sequence from bottom to top; wherein, the foam layer has adhesiveness, and the foam layer is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5 - 50 parts of elastic particles, 0.35 - 1 part of a curing agent, and 0.3 part of a black paste.

[0009] In an implementable embodiment, the foam layer is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5 - 30 parts of elastic particles, 0.35 - 0.75 part of a curing agent, and 0.3 part of a black paste;

[0010] The solid content of the acrylic base material is 20% - 50%, the viscosity is 9000 - 16000 cps, the storage modulus is 10 - 35 Kpa, the glass transition temperature TG is -20 °C to -35 °C, the creep recovery rate at 25 °C is 90 - 100%, and the material of the acrylic base material is polyacrylate;

[0011] The particle size of the elastic particles is 5-50 μm, the compressive strength of the elastic particles is 150-250 MPa, and the density of the elastic particles is 0.3-0.8 g / cm 3 .

[0012] In an implementable embodiment, the thickness of the adhesive layer is 20-50 μm, and the thickness of the foam layer is 50-110 μm.

[0013] In an implementable embodiment, the thickness of the adhesive layer is 30-50 μm, and the thickness of the foam layer is 80-100 μm.

[0014] In an implementable embodiment, the mesh release film includes a substrate layer, a resin mesh layer, and a release layer that are stacked in sequence from bottom to top; a mesh structure is formed on one side of the resin mesh layer in contact with the release layer, and the mesh structure is composed of a plurality of uniformly arranged hexagonal meshes connected to each other; the groove ridges formed between adjacent hexagonal meshes converge at the vertex positions of the hexagonal meshes to form a node structure, and the diameter of the circumscribed circle of the node structure is 15-30 μm.

[0015] In an implementable embodiment, the depth of the groove ridge is 5-10 μm, and the width of the groove ridge is 19-25 μm.

[0016] In an implementable embodiment, the resin mesh layer is configured to be deformable at a temperature of at least 100 °C. The resin mesh layer is formed by photocuring of a UV resin solution. The UV resin solution includes the following raw materials in parts by weight: 100 parts of UV glue, 3-12 parts of UV crosslinking agent, and 3-4 parts of UV initiator; among them, the UV crosslinking agent is one or a mixture of more than one of a bifunctional UV crosslinking agent, a trifunctional UV crosslinking agent, and a tetrafunctional UV crosslinking agent.

[0017] In an implementable embodiment, the bifunctional UV crosslinking agent is one or a mixture of more than one of polyethylene glycol 400 diacrylate, 1,6-hexanediol diacrylate, and polyurethane-modified diallyl oligomer;

[0018] The trifunctional UV crosslinking agent is one or a mixture of more than one of trimethylolpropane tris[3-(2-methylaziridinyl)propionate], trimethylolpropane triacrylate, and pentaerythritol triacrylate;

[0019] The tetrafunctional UV crosslinking agent is one or a mixture of more than one of pentaerythritol tetraallyl ether and tetrafunctional polyester acrylate;

[0020] The UV initiator is one or a mixture of more than one of 1-hydroxycyclohexyl phenyl ketone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthone, and isopropylthioxanthone.

[0021] In one feasible embodiment, the method for preparing the mesh release film includes:

[0022] Transfer and coat the UV resin solution onto the surface of the substrate layer through an anilox roll, and then perform primary UV curing, thereby initially forming a resin mesh layer with a mesh structure on the surface of the substrate layer. The UV exposure dose during primary UV curing is 500~2000 mj / cm 2 ;

[0023] Perform secondary UV curing and molding on the substrate layer with the resin mesh layer formed on its surface; wherein the UV exposure dose during secondary UV curing is 500~2000 mj / cm 2 ;

[0024] Coat a release agent on the mesh structure surface of the resin mesh layer to form a release layer.

[0025] According to the second aspect of the present disclosure, a substrate-free composite tape is provided, which includes the substrate-free foam tape described above, and further includes an adherend layer, and the adherend layer is bonded to the foam layer.

[0026] In one feasible embodiment, the adherend layer is a copper foil layer.

[0027] Compared with the prior art, the advantages of the present application are as follows: 1) In the present application, an acrylic base material, elastic particles, etc. are mixed in a certain proportion, so that the prepared foam layer has adhesiveness, has good adhesion to the adherend layer, and at the same time can make the modulus of the foam layer meet the requirements, so that the foam layer and the entire foam tape have good impact resistance and anti-film printing effect. Thus, the foam tape of the present application can not only omit the settings of the PET printed black film layer and the anti-adhesive coating, but also omit the acrylic adhesive layer in the copper foil tape layer, meeting the requirements of thinning, impact resistance, and anti-film printing while reducing the production cost.

[0028] 2) The number of processes of the substrate-free foam tape in the present application is significantly reduced. The production process is reduced from 5 processes to 3 processes, and at the same time, the number of processes of the adherend layer is reduced, and the coating process of the adherend layer is directly removed, effectively improving the yield rate and making it more cost-effective.

[0029] 3) When the size of the node structure on the mesh structure of the mesh release film in the present application is limited within the range of 15~30μm, it can cooperate with the width and depth of the groove rib, so that the bubbles in the exhaust groove on the pressure-sensitive adhesive can be discharged within a preset time, and the exhaust groove can also disappear within a preset time.

[0030] 4) The resin grid layer of this application is formed by photocuring of UV resin liquid, enabling the resin grid layer to be heat-resistant (the temperature remains unchanged at 90 - 150 °C, and it can even remain unchanged above 150 °C). Therefore, when an adhesive is coated on the grid release film and dried to form a pressure-sensitive adhesive layer, it can ensure that the entire grid release film does not deform, the grid structure does not deform, thus ensuring that the depth of the exhaust grooves formed on the surface of the pressure-sensitive adhesive is consistent, and ensuring the exhaust stability and disappearability of the exhaust grooves.

[0031] 5) This application adopts a coating process, which has more advantages in controlling dimensions and appearance compared with the existing conventional film coating process. The UV curing and embossing are faster and more thorough, and the depth and width data of the formed grid structure are more stable.

[0032] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features, and advantages of the exemplary embodiments of the present disclosure will become easily understood. In the drawings, several embodiments of the present disclosure are shown in an exemplary rather than restrictive manner, where:

[0034] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0035] Figure 1 Shows a schematic structural diagram of a substrate-free foam tape according to an embodiment of the present disclosure;

[0036] Figure 2 Shows a schematic structural diagram of a substrate-free composite tape according to an embodiment of the present disclosure;

[0037] Figure 3 Shows a schematic structural diagram of a foam layer according to an embodiment of the present disclosure (where Figure 3 Figure (a) is a schematic structural diagram of the foam layer, Figure 3 Figure (b) is a schematic diagram of the impact force transmission direction when the foam layer is subjected to a point impact force);

[0038] Figure 4 Shows a schematic structural diagram of a grid release film and a pressure-sensitive adhesive layer according to an embodiment of the present disclosure;

[0039] Figure 5 Shows a top view of a grid release film according to an embodiment of the present disclosure under a microscope;

[0040] Figure 6 Shows a schematic diagram of a node structure formed by the intersection of the pressure grooves and ridges of a grid structure according to an embodiment of the present disclosure;

[0041] Figure 7 Shows the node structure formed by the intersection of the grooved ridges in the first case of the embodiments of the present disclosure;

[0042] Figure 8 Shows the node structure formed by the intersection of the grooved ridges in the second case of the embodiments of the present disclosure;

[0043] Figure 9 Shows the node structure formed by the intersection of the grooved ridges in the third case of the embodiments of the present disclosure;

[0044] Figure 10 Shows the layout schematic diagram of the grid structure composed of hexagonal grids and the grid structure composed of quadrilateral grids in the embodiments of the present disclosure.

[0045] Reference numerals in the drawings: 1 - grid release film, 2 - pressure - sensitive adhesive layer, 3 - foam layer, 4 - adherend layer, 11 - substrate layer, 12 - resin grid layer, 13 - grid structure, 14 - release layer, 21 - second planar adhesive layer, 22 - micro - structure adhesive layer, 121 - first planar adhesive layer, 131 - hexagonal grid, 132 - grooved ridge, 133 - node structure, 221 - exhaust groove. Detailed implementation manners

[0046] To make the objectives, features, and advantages of the present disclosure more obvious and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present disclosure.

[0047] According to the first aspect of the present disclosure, as Figure 1 shown, the present invention provides a substrate - free foam tape (abbreviated as "foam tape" hereinafter), which includes a grid release film 1, an adhesive layer, and a foam layer 3 stacked in sequence from bottom to top; wherein, the foam layer 3 has adhesiveness, and the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5 - 50 parts of elastic particles, 0.35 - 0.1 part of curing agent, and 0.3 part of black paste.

[0048] For example, the adhesive layer is a pressure - sensitive adhesive layer 2, and preferably, the pressure - sensitive adhesive layer 2 is an acrylic pressure - sensitive adhesive layer.

[0049] Preferably, the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5 - 30 parts of elastic particles, 0.35 - 0.75 parts of a curing agent, and 0.3 parts of a black paste. Exemplarily, the addition amount of the elastic particles is 5 parts, 15 parts, or 30 parts. The addition amount of the curing agent is 0.35 parts, 0.55 parts, or 0.75 parts.

[0050] For example, the main index for the anti - film printing of the foam tape is the CFD (Compression and Rebound Force) index. The smaller the CFD value, the more ideal the anti - film printing effect. Preferably, 25%CFD ≤ 400 Kpa and 50%CFD ≤ 900 Kpa.

[0051] More preferably, 25%CFD < 120 Kpa and 50%CFD < 450 Kpa, and the anti - film printing effect will be more ideal; the main indexes for the anti - impact performance are the point impact absorption rate and the surface impact absorption rate. The higher the absorption rate, the better the anti - impact performance.

[0052] For example, the acrylic base material is colorless and transparent, the solid content of the acrylic base material is 20 - 50%, the viscosity is 9000 - 16000 cps, the storage modulus of the acrylic base material is 10 - 35 Kpa, the glass transition temperature TG is - 20°C to - 35°C, the creep recovery rate at 25°C is 90 - 100%, and the material of the acrylic base material is polyacrylate.

[0053] The compressive strength of the elastic particles is 150 - 250 Mpa, the particle size is 5 - 50 μm, the inside of the elastic particles is hollow, and the density of the elastic particles is 0.3 - 0.8 g / cm 3 Exemplarily, the elastic particles are microsphere particles, the elastic particles are white flowable powders, the shape is spherical, the particle size is 5 - 15 μm, the density is 0.58 - 0.62 g / cm 3 the compressive strength is 193 MPa, the pH value is 8 - 9.5, the water content ≤ 0.5%, the floating rate ≥ 96%, and the main component is silicon dioxide.

[0054] Exemplarily, the curing agent is an aliphatic isocyanate trimer, and the model / manufacturer of the black paste is Xiyan C629.

[0055] The characteristics of the elastic particles and the acrylic base material are listed in Table 1 below.

[0056] Table 1 Characteristics of Elastic Particles and Acrylic Base Material

[0057]

[0058] In an alternative solution, the thickness of the adhesive layer is 20 - 50 μm, and the thickness of the foam layer 3 is 50 - 110 μm. Preferably, the thickness of the adhesive layer is 30 - 50 μm, and the thickness of the foam layer 3 is 80 - 100 μm.

[0059] The number of processes for the substrate-free foam tape in this embodiment is significantly reduced. The production processes are reduced from 5 to 3, and at the same time, the number of processes for the adherend layer is reduced. The gluing process for the adherend layer is directly removed, effectively improving the yield rate and making it more cost-effective.

[0060] Specifically, in this embodiment, first, the PET printed black film layer (abbreviated as PET layer, i.e., the printed film) and the anti-adhesive coating commonly used in the existing foam tape are removed, and only the necessary pressure-sensitive adhesive layer and foam layer are retained, so as to meet the requirements of the application side for lightweight design. Among them, the removal of the PET printed black film layer can reduce the thickness by 5% and greatly reduce the overall modulus of the foam tape, improving the anti-film printing performance. This is because the modulus of the PET printed black film layer is thousands of times that of the foam layer and the pressure-sensitive adhesive layer, so removing the PET layer can greatly reduce the overall modulus. Secondly, in this application, the foam layer 3 is designed to be sticky, which not only reduces the thickness of the anti-adhesive coating but also reduces the thickness of the acrylic adhesive layer in the adherend layer (such as the copper foil tape layer), so that the foam layer is directly bonded and fixed to the copper foil layer. This design reduces the thickness by a total of 11%.

[0061] However, there are technical difficulties in the design here: First, the simultaneous removal of the PET printed black film layer and the anti-adhesive coating makes the pressure-sensitive adhesive layer 2 and the foam layer 3 in direct contact; therefore, we not only need to consider the reduction in thickness but also the feasibility of the process, as well as the compatibility and adhesion between the foam layer 3 and the pressure-sensitive adhesive layer 2. At the same time, it is also necessary to consider whether the foam layer 3 and the pressure-sensitive adhesive layer 2 will affect each other, resulting in performance variation. Second, not only the impact resistance of the foam layer 3 needs to be considered, but also the adhesion strength between the foam layer 3 and the adherend layer 4 (such as the copper foil layer). These two designs are somewhat contradictory, so the research and development of the base material of the foam layer 3 is very difficult.

[0062] Through a large number of creative experiments, we mixed acrylic base materials and elastic particles in a certain proportion, so that the prepared foam layer 3 has adhesiveness, has good adhesion to the adherend layer 4 (such as the copper foil layer), and at the same time can make the modulus of the foam layer 3 meet the requirements, so that the foam layer 3 and the entire foam tape have good impact resistance and anti-film printing effect. Thus, the foam tape of this application can not only omit the setting of the PET printed black film layer and the anti-adhesive coating, but also omit the setting of the acrylic adhesive layer in the copper foil tape layer, meeting the requirements of thinning, impact resistance, and anti-film printing while reducing the production cost.

[0063] Among them, the modulus of the acrylic base material and the elastic particles are screened, and it is found that in terms of impact resistance, in the substrate-free foam tape of this embodiment, a very low-modulus acrylic base material and relatively hard hollow elastic particles are used, and they are mixed in a higher proportion of the elastic particle concentration. The formed foam layer 3 will form a support framework on the surface of the pressure-sensitive adhesive layer 2, and the elastic particles are filled therein to play a role in relieving the impact force. Among them, due to the use of a low-modulus acrylic base material, the modulus of the foam layer is lower. After receiving the same impact force, the deformation will be more rapid and the amount of deformation will be larger. And the high-concentration, relatively hard hollow elastic particles can spread the impact force absorbed by the base material to the plane horizontally through mutual collision, thereby reducing the impact on the underlying functional layer, such as Figure 3 in Figure (a) of Figure 3 shown in Figure (b) of. Thus, the foam layer 3 of this application has better impact absorption when the thickness is relatively thin. It can be compared to the foam layer and springs in a Simmons mattress.

[0064] In terms of anti-film printing, in the foam layer 3 of this application, when the acrylic base material with a low modulus is under the same pressing distance, the pressure transmitted to the functional layer will be less than that of the acrylic base material with a high modulus. This is also the reason for the excellent performance of the substrate-free foam tape of this application after being thinned in terms of anti-film printing.

[0065] In summary, the innovative structural design of this application effectively reduces the thickness of the product, improves the anti-film printing performance, reduces costs, and improves the yield rate of the application end, making the product more cost-effective. Through the innovative design of the acrylic base material and elastic particles, this application simultaneously solves the two market demands of thickness reduction and anti-film printing.

[0066] In some embodiments, such as Figure 1 、 Figure 3 - 6 shown, the grid release film 1 includes a substrate layer 11, a resin grid layer 12, and a release layer 14 that are stacked in sequence from bottom to top; a grid structure 13 is formed on one side of the resin grid layer 12 in contact with the release layer. The grid structure 13 is composed of a plurality of uniformly arranged hexagonal grids 131 connected to each other. There are pressure groove ridges 132 formed between adjacent hexagonal grids. The pressure groove ridges 132 formed between adjacent hexagonal grids meet at the top corner positions of the hexagonal grids to form a node structure 133. The diameter of the circumscribed circle of the node structure 133 is 15 - 30 μm, the depth of the pressure groove ridge 132 is 5 - 10 μm, and the width of the pressure groove ridge 132 is 19 - 25 μm.

[0067] As Figure 6 shown. The pressure groove ridges 132 between three adjacent hexagonal grids 131 meet at one of the top corner positions of the hexagonal grids to form a node structure 133, and the shape of this node structure is triangular. When the size of the node structure is slightly smaller, such as Figure 7As shown, near the intersection point, the two sides of the grooved rib 132 gradually contract inward, and the shapes of the two sides are outwardly convex arcs, so that the width of the grooved rib gradually decreases, and thus the three grooved ribs intersect to form a node structure 133.

[0068] Alternatively, it can also be that near the intersection point, as Figure 8 shown, the two sides of the grooved rib 132 gradually expand outward, and the shapes of the two sides are generally inwardly concave arcs, so that the width of the grooved rib gradually increases, and thus the three grooved ribs intersect to form a node structure 133.

[0069] Or, it can also be that, as Figure 9 shown, the width of the grooved rib 132 does not change.

[0070] In summary, near the node structure 133, a transition section is formed between the grooved rib 132 and the node structure 133. Towards the direction close to the node structure 133, the width of this transition section gradually decreases, or it can also be that the width of the transition section gradually increases, or it can also be that the width of the transition section remains unchanged.

[0071] The above need to be adjusted accordingly according to the width of the grooved rib and the size of the node structure.

[0072] Since the resin mesh layer is formed by gravure transfer of a gravure roll, the corresponding texture pattern can be pre-engraved on the surface of the gravure roll according to the shape and size of the exhaust grooves on the surface of the pressure-sensitive adhesive layer 2, and the structure and shape of this texture pattern correspond to the mesh structure.

[0073] Exemplarily, the depth of the grooved rib 132 can be 5μm, 8μm, 10μm. The width of the grooved rib 132 can be 19μm, 22μm, 25μm. The diameter of the circumscribed circle of the node structure 133 can be 15μm, 20μm, 25μm, 30μm. In this application, the so-called "circumscribed circle of the node structure" is the circumscribed circle of the virtual triangle formed by the connection lines between the top angles of the adjacent hexagons at the intersection position. That is, the circumscribed circle of the virtual triangle formed by the wide sides (in the width direction) of the adjacent grooved ribs at the intersection position.

[0074] For example, as Figure 6 shown, the hexagonal mesh in this embodiment can be a regular hexagon, and the side length of the hexagonal mesh is 160 - 180um.

[0075] For example, the material of the substrate layer 11 is one of PET, PI, BOPP, paper, and PEEK. The material of the release layer 14 is solvent-based silicone oil or solvent-free silicone oil. The material of the resin mesh layer 12 is a high-temperature resistant resin.

[0076] The thickness of the base material layer 11 is 25 - 188 μm. The thickness of the resin mesh layer 12 is 15 - 100 μm. The thickness of the release layer 14 is 0.5 - 1 μm.

[0077] We found that when the mesh structure 13 is composed of multiple uniformly arranged hexagonal meshes 131 connected to each other, accordingly, the exhaust grooves 221 formed on the surface of the pressure - sensitive adhesive layer 2 are hexagonal exhaust grooves, and these hexagonal exhaust grooves are interconnected through exhaust nodes (when the node structure of the mesh release film is transferred to the pressure - sensitive adhesive layer, exhaust nodes will be formed on the surface of the pressure - sensitive adhesive layer), thus forming a mesh shape. Under the same conditions, the number of hexagonal exhaust grooves and exhaust nodes is more than that of the currently conventional quadrilateral exhaust grooves. And the more the number of exhaust grooves and exhaust nodes, the better the exhaust effect. Therefore, the hexagonal exhaust grooves are superior to the quadrilateral exhaust grooves in terms of exhaust effect.

[0078] Thus, in this embodiment, taking the mesh structure 13 composed of the arrangement of hexagonal meshes 131 as an example, compared with the currently conventional mesh structure composed of the arrangement of quadrilateral meshes in the market, as Figure 10 shown, the hexagonal - mesh - shaped exhaust grooves and quadrilateral - mesh - shaped exhaust grooves formed by transferring them to the surface of the pressure - sensitive adhesive layer 2 are analyzed respectively. We select hexagonal exhaust grooves and quadrilateral exhaust grooves with the same conditions and the same area for arrangement, and the results show that the rule of increasing exhaust nodes is (the number and exhaust node rules of the quadrilateral exhaust grooves and hexagonal exhaust grooves shown in Table 2): 1) When the number of quadrilateral exhaust grooves increases to an odd number, one exhaust node is added. When the number of quadrilateral exhaust grooves increases to an even number, two exhaust nodes are added. 2) As long as the number of hexagonal exhaust grooves increases by one, the corresponding number of exhaust nodes will increase by two. Therefore, for the mesh release film, a polygon needs to be selected, and the following two points need to be achieved: First, it can be densely arranged without blank areas, and the exhaust grooves form a continuous channel without breakpoints. Second, the number of exhaust grooves and exhaust nodes should be as many as possible. Therefore, the best choice meeting these two points is the hexagonal exhaust groove. Correspondingly, on the mesh release film, the mesh unit forming the mesh structure is preferably a hexagonal mesh.

[0079] Table 2 Rules of the number and exhaust nodes of the existing conventional quadrilateral exhaust grooves and the hexagonal exhaust grooves of the present application

[0080]

[0081] Specifically, the side of the resin mesh layer 12 in contact with the release layer 14 is a mesh structure 13 in the shape of a mesh. The mesh structure 13 is composed of a plurality of uniformly arranged hexagonal meshes 131 connected to each other. Substantially, these hexagonal meshes are arranged and connected in the shape order of a hexagon by the grooved ridges 132, so that adjacent hexagonal meshes share a grooved ridge 132. The grooved ridges between adjacent hexagonal meshes meet at the apex positions of the hexagon to form a node structure 133, and these grooved ridges are connected to each other through the node structure. Thus, when the pressure-sensitive adhesive layer 2 is laminated on the surface of the mesh release film 1, the grooved ridges 132 on the mesh structure can form corresponding hexagonal exhaust grooves in the shape of a mesh on the surface of the pressure-sensitive adhesive layer 2. These exhaust grooves also meet at the apex positions of the hexagon to form exhaust nodes, so that after the mesh release film is peeled off from the pressure-sensitive adhesive layer, the entire pressure-sensitive adhesive layer has hexagonal exhaust grooves in the shape of a mesh, enabling the pressure-sensitive adhesive layer to quickly discharge the bubbles in the exhaust grooves and make the exhaust grooves disappear within a preset time when it is attached to the item to be pasted.

[0082] In this application, the mesh structure 13 on the mesh release film is composed of hexagonal meshes 131 connected to each other as units. We found that, compared with the conventional quadrilateral mesh structure on the release film currently, under the same conditions, the more sides the polygon mesh has, the more exhaust nodes the exhaust grooves formed on the surface of the pressure-sensitive adhesive layer 2 have, and the exhaust effect shows a positive correlation. Since the mesh structure 13 is formed by transferring and coating the resin liquid onto the surface of the base material layer using a gravure roll, a pattern corresponding to the mesh structure 13 needs to be engraved on the gravure roll first. Considering the difficulty of implementing the pattern on the gravure roll, hexagonal meshes are preferably used.

[0083] When the exhaust grooves 221 formed on the surface of the pressure-sensitive adhesive layer 2 are attached to the item to be pasted, most of the bubbles in the exhaust grooves gather at the exhaust node positions. Currently, on the market, after the mesh release film is laminated with the pressure-sensitive adhesive layer, the bubbles in the exhaust grooves on the surface of the pressure-sensitive adhesive cannot be discharged and the exhaust grooves cannot disappear within the preset time during actual attachment to the item to be pasted. Through a large number of research experiments, we found that when the size of the node structure 133 (i.e., the diameter of the circumscribed circle of the node structure) on the mesh structure 13 of the mesh release film is limited within the range of 15 - 30 μm, it can cooperate with the width (19 - 25 μm) and depth (5 - 10 μm) of the grooved ridge 132 to enable the bubbles in the exhaust grooves 221 on the pressure-sensitive adhesive layer 2 to be quickly discharged, and the exhaust grooves 221 can also disappear within the preset time.

[0084] Moreover, when the mesh release film 1 is used in the preparation of a foam tape in combination with the pressure-sensitive adhesive layer 2, etc., a release layer 14 is first coated on the mesh structure of the resin mesh layer, so as to ensure that the mesh release film 1 can be peeled off from the pressure-sensitive adhesive layer 2. The thickness of the release layer 14 is generally 0.5 - 1 μm, and compared with the depth of the mesh structure, the thickness of the release layer 14 can be ignored. Therefore, when the mesh release film 1 composed of the substrate layer, the resin mesh layer, and the release layer is laminated with the pressure-sensitive adhesive layer 2, the size of the mesh structure can be completely transferred to the pressure-sensitive adhesive layer 2, forming corresponding hexagonal exhaust grooves in a grid pattern on the surface of the pressure-sensitive adhesive layer 2. Moreover, the depth, width of the hexagonal exhaust grooves on the pressure-sensitive adhesive layer, and the size of the exhaust nodes are equivalent to the depth of the groove ribs 132, the width of the groove ribs 132, and the size of the node structure 133 of the mesh structure 13.

[0085] Among them, we also found through research that the exhaustibility and disappearability of the exhaust grooves 221 on the surface of the pressure-sensitive adhesive layer 2 are a set of paradoxes and are mutually contradictory. If we want to ensure the exhaustibility of the exhaust grooves 221, we need to increase the physical size of the exhaust grooves (such as the depth and width of the exhaust grooves), but the increase in the physical size of the exhaust grooves 221 makes the difficulty of the disappearability of the exhaust grooves increase exponentially, which also means that the disappearability of the exhaust grooves cannot be achieved. And if we want to ensure the disappearability of the exhaust grooves, we need to appropriately reduce the physical size of the exhaust grooves, such as reducing the width and depth of the exhaust grooves, but the bubbles in the exhaust grooves cannot be discharged smoothly. Therefore, it is necessary to find a balance between exhaustibility and disappearability to ensure that these two performances can be achieved simultaneously. In addition, since most of the bubbles in the exhaust grooves gather at the exhaust node positions and are difficult to discharge, we found through a large number of orthogonal experiments that on the premise that the diameter of the circumscribed circle of the node structure 133 of the mesh release film is 15 - 30 μm, when the depth of the groove ribs 132 on the mesh release film is 5 - 10 μm and the width of the groove ribs 132 is 19 - 25 μm, it can make the exhaust grooves 221 transferred to the surface of the pressure-sensitive adhesive layer 2 quickly discharge the bubbles both in the channels of the exhaust grooves and in the exhaust nodes where the ends of the exhaust grooves meet when adhering to the item to be pasted, and at the same time, the exhaust grooves also disappear within the preset time.

[0086] For example, as Figure 4As shown, the resin mesh layer 12 includes a mesh structure 13 and a first planar adhesive layer 121. The first planar adhesive layer 121 is disposed between the mesh structure 13 and the substrate layer 11. The mesh structure 13 is provided on the side of the first planar adhesive layer 121 facing away from the substrate layer 11, and the mesh structure 13 protrudes from the first planar adhesive layer 121. The pressure-sensitive adhesive layer 2 includes a microstructured adhesive layer 22 and a second planar adhesive layer 21. The second planar adhesive layer 21 is located between the microstructured adhesive layer 22 and the foam layer 3. The microstructured adhesive layer 22 engages with the mesh structure 13 and the release layer 14 thereon. Exhaust grooves 221 are formed on the microstructured adhesive layer 22. The shapes of these exhaust grooves 221 are hexagonal, and the hexagonal exhaust grooves 221 communicate with each other to form a grid pattern. Thus, when a pressure-sensitive adhesive is coated on the release surface of the release layer 14 on the mesh structure to form the pressure-sensitive adhesive layer 2, these embossed ridges on the mesh structure are transferred to the surface of the pressure-sensitive adhesive layer, thereby forming grid-shaped exhaust grooves 221 on the surface of the pressure-sensitive adhesive layer 2.

[0087] In some embodiments, the resin mesh layer is configured to be deformable at a temperature of at least 100 °C. The resin mesh layer 12 is formed by photocuring of a UV resin solution. The UV resin solution includes the following raw materials in parts by weight: 100 parts of UV glue, 3 - 12 parts (phr) of UV crosslinking agent, and 3 - 4 parts of UV initiator; wherein, the UV crosslinking agent is one or a mixture of a difunctional UV crosslinking agent, a trifunctional UV crosslinking agent, and a tetrafunctional UV crosslinking agent.

[0088] For example, the UV glue can be an epoxy-based UV glue, and the selectable models include but are not limited to: Loctite EA3335, TSBD2640, Letop 3523.

[0089] The UV initiator can initiate a polymerization reaction when the material is irradiated with ultraviolet light. Exemplarily, the UV initiator is one or a mixture of 1-hydroxycyclohexyl phenyl ketone (PI-184), diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide (TPO), 2-isopropyl thioxanthone, and isopropyl thioxanthone (ITX105).

[0090] The difunctional UV crosslinking agent includes but is not limited to: polyethylene glycol 400 diacrylate (PEG400DA), 1,6-hexanediol diacrylate (HDDA, also known as "1,6-hexanediol diacrylate"), and polyurethane-modified diallyl oligomer (DOUBLEMER® 5222).

[0091] The trifunctional UV crosslinking agent includes but is not limited to: trimethylolpropane tris[3-(2-methylaziridinyl)propionate] (TTMAP), trimethylolpropane triacrylate (TMPTA), and pentaerythritol triacrylate (PETA).

[0092] The tetra-functional UV cross-linking agent includes, but is not limited to, pentaerythritol tetraallyl ether and tetra-functional polyester acrylate (ETERCURE 6325-100).

[0093] In this embodiment, the resin grid layer is formed by photocuring of the UV resin solution, so that the resin grid layer has high temperature resistance (the temperature remains unchanged at 90-150 °C, and it can even remain unchanged above 150 °C). Therefore, when an adhesive (i.e., a pressure-sensitive adhesive) is coated on the release layer surface of the grid release film and dried to form a pressure-sensitive adhesive layer, it can ensure that the entire grid release film does not deform, ensure that the grid structure does not deform, so as to ensure that the depth of the exhaust grooves formed on the surface of the pressure-sensitive adhesive layer is consistent, and ensure the exhaust stability and disappearability of the exhaust grooves.

[0094] For example, in this embodiment, the grid release film is specifically prepared by the following method: including:

[0095] The UV resin solution is transferred and coated onto the surface of the substrate layer through an anilox roll, and then UV pre-curing is carried out, so as to preliminarily form a resin grid layer with a grid structure on the surface of the substrate layer. The UV exposure amount during UV pre-curing is 500-2000 mj / cm 2 ;

[0096] The substrate layer with a resin grid layer formed on its surface is subjected to UV secondary curing and molding; wherein the UV exposure amount during UV secondary curing is 500-2000 mj / cm 2 ;

[0097] A release agent is coated on the grid structure surface of the resin grid layer to form a release layer.

[0098] In this embodiment, the UV resin solution is dropped onto the anilox roll, and the anilox roll transfers and coats the UV resin solution onto the surface of the substrate layer in a embossing form, and then UV pre-curing is carried out. After UV pre-curing, the resin grid layer is demolded from the anilox roll, and a resin grid layer with a grid structure is formed on the surface of the substrate layer. Then, further UV secondary curing is carried out to form the resin grid layer on the surface of the substrate layer, further ensuring the firm connection between the resin grid layer and the substrate layer. It can be seen from this that the materials of the resin grid layer and the grid structure formed on one side thereof are not only the same, but they are formed on the surface of the substrate layer by one-step and integral photocuring. Then, a release agent (such as silicone oil) is coated on the grid structure surface to form a release layer.

[0099] In this embodiment, the coating process has more advantages in controlling the size and appearance than the existing conventional casting process. The UV curing and embossing are faster and more thorough, and the depth and width data of the formed grid structure are more stable.

[0100] According to the second aspect of the present disclosure, as Figure 2 shown, the present invention provides a substrate-free composite tape, which includes a foam tape and also includes an adherend layer 4, and the adherend layer 4 is adhesively provided on the foam layer 3. Exemplarily, the adherend layer 4 can be a copper foil layer, an aluminum foil layer, a ceramic layer, etc., which can be adhered to the foam layer and are suitable for materials in the tape field. More preferably, the adherend layer 4 is a copper foil layer. With the composite tape structure of the foam tape of the present application, it is also possible to achieve a thinning effect while meeting the impact resistance and anti-film printing effect of the composite tape. In addition, when the substrate-free composite tape of the present application is actually adhered to an adherend, the air bubbles between the pressure-sensitive adhesive layer and the surface of the adherend can be quickly discharged, and the exhaust grooves on the surface of the pressure-sensitive adhesive layer can also disappear within a preset time.

[0101] The foam tape of the present application can be sold separately as an independent product. Of course, it can also be sold as a composite tape adhesively bonded to the adherend layer. Among them, when the foam tape is sold separately as an independent product, a release paper needs to be pre-stuck on the foam layer 3. When it needs to be specifically applied at the application end (such as on a curved screen of a mobile phone), first remove the release paper, and then bond and fix the foam layer 3 and the adherend layer 4 (such as a copper foil layer).

[0102] The following further elaborates on the present application with specific embodiments:

[0103] Example 1

[0104] 1): A substrate-free foam tape, which includes a mesh release film 1, a pressure-sensitive adhesive layer 2, and a foam layer 3 that are sequentially stacked from bottom to top; among them, the foam layer 3 has adhesiveness, and the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of an acrylic base material, 5 parts of elastic particles, 0.35 parts of a curing agent, and 0.3 parts of black paste.

[0105] Among them, the pressure-sensitive adhesive layer 2 is an acrylic pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer 2 is 30 μm, the thickness of the foam layer 3 is 100 μm, and the total thickness of the pressure-sensitive adhesive layer 2 and the foam layer 3 is 130 μm.

[0106] Among them, the material of the acrylic base material is polyacrylate, the solid content is 20%, the storage modulus is 10 KPa, the glass transition temperature Tg is -20 °C, the viscosity is 9000 cps, and the creep recovery rate at 25 °C is 90%;

[0107] The elastic particles are white flowable powders, the particle shape is spherical, the particle size of the elastic particles is 5 - 15 μm, the compressive strength is 193 MPa, the density is 0.58 - 0.62 g / cm 3 ³, the pH value is 8 - 9.5, the moisture content ≤ 0.5%, the floating rate ≥ 96%, and the main component is silicon dioxide.

[0108] The curing agent is an aliphatic isocyanate trimer.

[0109] The mesh release film 1 includes a substrate layer 11, a resin mesh layer 12, and a release layer 14 that are stacked in sequence from bottom to top. A mesh structure 13 is formed on one side of the resin mesh layer 12 that contacts the release layer 14. The mesh structure 13 is composed of a plurality of uniformly arranged hexagonal meshes 131 connected to each other. Groove ridges 132 are formed between adjacent hexagonal meshes. The groove ridges 132 between adjacent hexagonal meshes converge at the top corner positions of the hexagonal meshes to form a node structure 133. The shape of the node structure is triangular. The diameter of the circumscribed circle of the node structure is 15 - 30 μm, the depth of the groove ridge 132 is 5 - 10 μm, and the width of the groove ridge 132 is 19 - 25 μm.

[0110] Among them, the material of the substrate layer 11 is PET, and the resin mesh layer 12 is formed by photocuring of UV resin liquid. The UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 10 parts of bifunctional UV crosslinking agent, and 3 parts of UV initiator. Among them, the bifunctional UV crosslinking agent is polyethylene glycol 400 diacrylate, and the UV initiator is 1 - hydroxycyclohexyl phenyl ketone (PI - 184).

[0111] II): A preparation method of a substrate - free foam tape: It includes the following steps:

[0112] Step 1: Preparation of the mesh release film 1: Specifically including:

[0113] Step 1 - 1): Transfer - coat the UV resin liquid onto the surface of the substrate layer 11 through a gravure roll, and then perform UV pre - curing, so as to preliminarily form a resin mesh layer 12 with a mesh structure 13 on the surface of the substrate layer. The UV exposure amount during UV pre - curing is 500 mj / cm 2 ;

[0114] Step 1 - 2): Perform UV secondary curing and molding on the substrate layer with a resin mesh layer formed on its surface; among them, the UV exposure amount during UV secondary curing is 500 mj / cm 2 ;

[0115] Step 1 - 3): Coat a release agent on the mesh structure surface of the resin mesh layer to form a release layer 14.

[0116] Step 2: Preparation of the pressure - sensitive adhesive layer 2: Coat a pressure - sensitive adhesive on the surface of the release layer facing away from the substrate layer, so as to form a pressure - sensitive adhesive layer on the surface of the release layer.

[0117] Step 3: Prepare the foam layer 3, and then bond the foam layer and the pressure - sensitive adhesive layer together to finally obtain a substrate - free foam tape.

[0118] Example 2

[0119] Example 2 is generally the same as Example 1, except that the UV resin solution comprises raw materials in the following parts by weight: 100 parts of UV glue, 6 parts of difunctional UV crosslinking agent, 2 parts of trifunctional UV crosslinking agent, and 4 parts of UV initiator. Among them, the UV exposure amount during UV primary curing and UV secondary curing is both 1000 mj / cm 2 The difunctional UV crosslinking agent is 1,6 - hexanediol diacrylate, the trifunctional UV crosslinking agent is trimethylolpropane triacrylate, and the UV initiator is diphenyl - (2,4,6 - trimethylbenzoyl) phosphine oxide (TPO).

[0120] Example 3

[0121] Example 3 is generally the same as Example 1, except that the UV resin solution comprises raw materials in the following parts by weight: 100 parts of UV glue, 5 parts of trifunctional UV crosslinking agent, and 3 parts of UV initiator. Among them, the UV exposure amount during UV primary curing and UV secondary curing is both 1500 mj / cm 2 The trifunctional UV crosslinking agent is pentaerythritol triacrylate, and the UV initiator is isopropylthioxanthone ITX1105.

[0122] Example 4

[0123] Example 4 is generally the same as Example 1, except that the UV resin solution comprises raw materials in the following parts by weight: 100 parts of UV glue, 3 parts of tetrafunctional UV crosslinking agent, and 4 parts of UV initiator. Among them, the UV exposure amount during UV primary curing and UV secondary curing is both 1000 mj / cm 2 The tetrafunctional UV crosslinking agent is pentaerythritol tetraallyl ether, and the UV initiator is 1 - hydroxycyclohexyl phenyl ketone (PI - 184).

[0124] Example 5

[0125] Example 5 is generally the same as Example 1, except that the UV resin solution comprises raw materials in the following parts by weight: 100 parts of UV glue, 5 parts of difunctional UV crosslinking agent, 4 parts of trifunctional UV crosslinking agent, 3 parts of tetrafunctional UV crosslinking agent, and 3 parts of UV initiator. Among them, the UV exposure amount during UV primary curing and UV secondary curing is both 2000 mj / cm 2 The difunctional UV crosslinking agent is polyurethane - modified diallyl oligomer DOUBLEMER® 5222, the trifunctional UV crosslinking agent is pentaerythritol triacrylate, the tetrafunctional UV crosslinking agent is tetrafunctional polyester acrylate ETERCURE 6325 - 100, and the UV initiator is diphenyl - (2,4,6 - trimethylbenzoyl) phosphine oxide (TPO).

[0126] Example 6

[0127] Example 6 is generally the same as Example 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 part of curing agent, and 0.3 part of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12000 cps, and a creep recovery rate at 25 °C of 94%.

[0128] Example 7

[0129] Example 7 is generally the same as Example 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 30 parts of elastic particles, 0.75 part of curing agent, and 0.3 part of black paste; the acrylic base material is polyacrylate, with a solid content of 50%, a storage modulus of 35 KPa, a glass transition temperature Tg of -20 °C, a viscosity of 16000 cps, and a creep recovery rate at 25 °C of 98%.

[0130] Example 8

[0131] Example 8 is generally the same as Example 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 40 parts of elastic particles, 1 part of curing agent, and 0.3 part of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12000 cps, and a creep recovery rate at 25 °C of 94%.

[0132] Example 9

[0133] Example 9 is generally the same as Example 1, except that: the thickness of the adhesive layer is 20 μm, and the foam layer is 110 μm; the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 part of curing agent, and 0.3 part of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12000 cps, and a creep recovery rate at 25 °C of 94%.

[0134] Example 10

[0135] Example 10 is generally the same as Example 1, except that the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 part of curing agent, and 0.3 part of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12000 cps, and a creep recovery rate at 25 °C of 94%.

[0136] Example 11

[0137] This Example 11 is substantially the same as Example 1, except that: the thickness of the adhesive layer is 50 μm, and the thickness of the foam layer is 80 μm; the foam layer 3 is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 15 parts of elastic particles, 0.55 parts of curing agent, and 0.3 parts of black paste; the acrylic base material is polyacrylate, with a solid content of 40%, a storage modulus of 25 KPa, a glass transition temperature Tg of -35 °C, a viscosity of 12,000 cps, and a creep recovery rate of 94% at 25 °C.

[0138] Comparative Example 1

[0139] This Comparative Example 1 is substantially the same as Example 1, except that: the addition amount of elastic particles is 0 part.

[0140] Relevant performance tests

[0141] Next, relevant performance tests are carried out on the substrate-free foam tape prepared in each example.

[0142] I): The composition components of the resin mesh layer in Examples 1 - 5 are listed in Table 3.

[0143] Table 3 Composition component table of the resin mesh layer

[0144]

[0145] And a heat resistance experiment is carried out on the mesh release film prepared in Examples 1 - 5, and the results are shown in Table 4:

[0146] Table 4 Heat resistance test results of the mesh release film in Examples 1 - 5

[0147]

[0148] It can be concluded from Table 4 that the resin mesh layer prepared by using the UV resin liquid of the present application, and the entire mesh release film can remain unchanged and be high-temperature resistant at 90 - 150 °C. Thus, it is ensured that the exhaust grooves formed on the pressure-sensitive adhesive layer are of uniform depth, and the exhaustibility and disappearability of the exhaust grooves are ensured.

[0149] II): Experiment on the correlation between the physical dimensions of the pressing groove ridges 132 and the node structure 133 dimensions of the mesh structure 13 of the mesh release film and the exhaustibility and disappearability of the exhaust grooves of the pressure-sensitive adhesive layer 2.

[0150] Next, we further explore the correlation between the physical dimensions of the grooved ridges 132 (such as depth and width) and the dimensions of the node structure 133 on the exhaustibility and disappearability of the exhaust grooves formed on the pressure-sensitive adhesive layer: taking the circumscribed circle diameter of the node structure 133, the depth of the grooved ridges 132, and the width of the grooved ridges 132 as variables, with other conditions being the same (such as all using hexagonal grids, the composition and thickness of the UV resin grid layer being the same, the material of the substrate layer being the same, etc.), to explore the correlation between the physical dimensions of the grooved ridges and the exhaustibility and disappearability of the exhaust grooves on the pressure-sensitive adhesive layer, that is, to conduct a correlation orthogonal experiment (where the influence factor table is shown in Table 5), and the orthogonal experiment results are shown in Table 6:

[0151] Table 5 Influence Factor Scheme Table

[0152]

[0153] Table 6 Orthogonal Experiment Results

[0154]

[0155] Note: For both the exhaust effect and the disappearability effect, performance tests need to be carried out after making the tape product. This orthogonal experiment is evaluated by making the same kind of single-sided disappearable reticulated tape (i.e., a single-sided grid tape, at least including a grid release film, a pressure-sensitive adhesive, and a substrate layer stacked in sequence from bottom to top). The evaluation criteria are shown in Table 7:

[0156] Table 7 Evaluation Criteria for the Exhaustibility and Disappearability of the Exhaust Grooves on the Pressure-Sensitive Adhesive Layer

[0157]

[0158] Note: The reticulation in Table 7 refers to the grid-shaped exhaust grooves.

[0159] Among them, (1): Exhaustibility test: Place the made single-sided disappearable reticulated tape in an environment with a temperature of 23 ± 2°C and a humidity of 65 ± 5%, and cut the single-sided disappearable reticulated tape into a size of 50 mm × 50 mm. Then attach the adhesive layer of the tape to a glass plate, and quickly rotate and press clockwise with your finger at the bubbling place in the middle of the tape to see its exhaust speed and whether it can exhaust air.

[0160] (2): Disappearability test: Cut the made single-sided disappearable reticulated tape into a size of 50 × 50 mm. Tear off the grid release film on the tape, and flatten the grid adhesive surface on a white glass; roll it back and forth 3 times with a 2 kg rubber roller (at a speed of 25 mm / sec). Place the attached sample in a normal temperature environment, and observe the disappearance of the reticulation every 1 hour with an LED lamp and a magnifying glass, and record the disappearance time (observe all positions and record the disappearance time after determining that the reticulation has completely disappeared).

[0161] It can be seen from Table 6 that the exhaust effect and the disappearable effect of Experimental Groups 3 / 4 / 6 / 7 / 8 / 11 / 12 / 14 / 16 / 18 / 19 / 22 meet the requirements. In particular, the exhaust effect and the disappearable effect of Experimental Groups 7 / 14 / 18 are the best. Thus, through Tables 5-7, it can be obtained that when the circumscribed circle diameter of the node structure 133 of the mesh release film is 15-30 μm, the depth of the grooved rib 132 is 5-10 μm, and the width of the grooved rib 132 is 19-25 μm, it can enable the air bubbles in the exhaust groove 221 on the surface of the pressure-sensitive adhesive layer 2 to be discharged and the exhaust groove can also be ensured to completely disappear when being attached to the object to be pasted.

[0162] III): Test the elastic modulus, impact resistance, and CFD of the foam tapes prepared in Example 1 and Examples 6-8, as well as the adhesion between the adhesive layer and the foam layer and the adhesion between the foam layer and the copper foil layer (i.e., the layer to be pasted 4). The results are shown in Table 8 below:

[0163] Among them, for the test of the point impact absorption rate: 1) Take the sample to be tested with a size of 75 mm×75 mm and paste it on a 75 mm×75 mm glass plate with a thickness of 0.7 mm; 2) Take a 4.3 g steel ball, adjust the falling height of the steel ball to 10.1 cm, the steel ball is magnetically adsorbed, and the platform below the steel ball is made of stainless steel with a sensor to test the initial impact force. To reduce equipment errors, 3 groups of point impact blank tests need to be tested as the control group to ensure that the values of the 3 groups of blank tests are similar and take the average value to finally obtain the initial impact force; 3) After the blank test is completed, place the glass plate with the sample to be tested attached on it with the glass surface facing down and the foam surface facing up in the middle of the stainless steel platform, and test the point impact force. Conduct 3 tests to obtain 3 groups of point impact force values and take the average value to obtain the impact force II; 4) According to the formula: ((initial impact force - impact force II) / initial impact force)×100%, calculate to obtain the point impact absorption rate.

[0164] For the adhesion test: Taking the adhesion test between the adhesive layer and the foam layer as an example, attach the adhesive layer of the foam tape to the test plate. After rolling it 3 times with a pressure roller, attach the traction tape flatly to the non-test surface of the foam layer. Then fix the test plate on the moving fixture of the tensile machine and fix the traction tape on the fixed fixture, and peel it at an angle of 180° and a speed of 300 mm / min to test the adhesion between the adhesive layer and the foam layer.

[0165] The adhesion between the foam layer and the copper foil layer is also tested with reference to the above method.

[0166] For the CFD test: Stack the foam tape without the mesh release film to about 10 mm, and then place it on the compression platform to test the compression and rebound forces at a compression ratio of 25% and 50%.

[0167] Table 8 Performance test results of the foam tapes prepared in each example and comparative example

[0168]

[0169] It can be concluded from Table 8 that the foam tapes prepared in Example 1 and Examples 6 - 8 of the present invention have good point impact absorption rate, CFD value and elastic modulus. Moreover, the adhesion between the prepared foam layer and the copper foil layer is above 1500 g / 25mm. In particular, the adhesion between the foam layer and the copper foil layer in Example 1 and Examples 6 - 7 is above 3000 g / 25mm, meeting the optimal standard of users. Among them, in terms of adhesion, the foam layer in the foam tape prepared in Example 8 is much smaller than that of other examples. Although its point impact absorption rate value is the highest, considering the adhesion, point impact absorption rate and CFD value comprehensively, we find that the foam tape composed of a foam layer prepared from 100 parts of acrylic base material, 5 - 30 parts of elastic particles, 0.35 - 0.75 parts of curing agent and 0.3 part of black paste can better meet the production requirements. More preferably, considering the three indicators of adhesion, point impact absorption rate and CFD value comprehensively, we further find that the comprehensive indicators of the foam tape prepared in Example 6 reach the optimum.

[0170] IV): In the present application, the thicknesses of the pressure - sensitive adhesive layer 2 and the foam layer 3 can be combined in various thicknesses according to user requirements. The distribution of the thicknesses of the pressure - sensitive adhesive layer and the foam layer is determined through experiments according to performance requirements. Taking a foam tape with a total thickness of 130μm for the pressure - sensitive adhesive layer and the foam layer as an example, the experimental data of the adhesion between the pressure - sensitive adhesive layer and the foam layer, the adhesion between the foam layer and the adherend (copper foil layer), the point impact absorption rate of the foam tape, CFD, and the disappearability of the mesh pattern of the grid release film for the foam tapes prepared with different thicknesses of the pressure - sensitive adhesive layer and the foam layer are shown in Table 9 below:

[0171] Table 9 Related experimental data of the foam tape

[0172]

[0173] As can be seen from Table 9, among the foam tapes prepared in Examples 9-11, the adhesion between the foam layer and the copper foil layer (the adhered layer) has a small difference, and is much greater than the optimal standard of 2000 g / 25mm, all meeting the user's optimal standard. The adhesion between the adhesive layer and the foam layer varies slightly due to the thickness of the adhesive layer, but all can also meet the user's optimal standard. The foam tapes prepared in Examples 9-11 have a slightly smaller difference in terms of the point impact absorption rate, but a relatively large difference in CFD values. Among them, the CFD values of Examples 10-11 are better, especially the CFD value of Example 11 is the best, being the most ideal in terms of the anti-film printing effect, and the screen pattern disappearance time is also much lower than that of Example 9. Considering the point impact absorption rate, CFD, and the screen pattern disappearance time comprehensively, the foam tapes prepared in Examples 10-11 have better performance. Therefore, when the adhesive layer is 30-50μm and the foam layer is 80-100μm, the screen pattern on the adhesive layer of the prepared foam tape can quickly disappear when adhering to the adhered article, and can completely disappear in as little as 2-3 hours, and the foam tape has good anti-impact and anti-film printing effects.

[0174] It should be understood that various forms of the processes shown above can be used, reordering, adding, or deleting steps. For example, the steps recorded in the present disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved, and no limitations are imposed herein.

[0175] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present disclosure, "a plurality" means two or more, unless otherwise specifically defined. As described above, these are only the specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should all be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A substrate-free foam tape, characterized in that: The invention comprises a grid release film, a glue layer and a foam layer which are stacked in sequence from bottom to top; wherein the foam layer is sticky and is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5-50 parts of elastic particles, 0.35-1 parts of curing agent and 0.3 parts of black paste; the particle size of the elastic particles is 5-50 μm, the compressive strength of the elastic particles is 150-250 MPa, and the density of the elastic particles is 0.3-0.8 g / cm 3 ; The grid release film comprises a substrate layer, a resin grid layer and a release layer stacked in sequence from bottom to top; a grid structure is formed on the side of the resin grid layer in contact with the release layer, and the grid structure is composed of a plurality of hexagonal grids connected to each other; the grooved convex strips formed between adjacent hexagonal grids intersect at the vertex positions of the hexagonal grids to form a node structure, the circumscribed circle diameter of the node structure is 15-30 μm, the depth of the grooved convex strips is 5-10 μm, and the width of the grooved convex strips is 19-25 μm; the circumscribed circle diameter of the node structure is the circumscribed circle of a virtual triangle formed by the wide sides of adjacent grooved convex strips at the intersection position; The resin grid layer is configured to be able to remain unchanged at a temperature of at least 100°C. The resin grid layer is formed by photocuring with UV resin liquid, and the UV resin liquid includes the following raw materials in parts by weight: 100 parts of UV glue, 3 to 12 parts of UV cross-linking agent, and 3 to 4 parts of UV initiator; wherein the UV cross-linking agent is a mixture of one or more of a bifunctional UV cross-linking agent, a trifunctional UV cross-linking agent, and a tetrafunctional UV cross-linking agent.

2. The substrate-free foam tape according to claim 1, characterized in that: The foam layer is prepared from the following raw materials in parts by weight: 100 parts of acrylic base material, 5-30 parts of elastic particles, 0.35-0.75 parts of curing agent and 0.3 parts of black paste; The acrylic base material has a solid content of 20% to 50%, a viscosity of 9000 to 16000 cps, a storage modulus of 10 to 35 Kpa, a glass transition temperature TG of -20°C to -35°C, a creep recovery rate of 90 to 100% at 25°C, and the material of the acrylic base material is polyacrylate.

3. The substrate-free foam tape according to claim 1, characterized in that: The thickness of the adhesive layer is 20-50um, and the thickness of the foam layer is 50-110um.

4. The substrate-free foam tape according to claim 3, characterized in that: The thickness of the adhesive layer is 30-50 μm, and the thickness of the foam layer is 80-100 μm.

5. The substrate-free foam tape according to claim 1, characterized in that: The bifunctional UV crosslinking agent is a mixture of one or more of polyethylene glycol 400 diacrylate, 1,6-hexanediol diacrylate, and polyurethane modified diacrylate oligomer; The trifunctional UV crosslinking agent is a mixture of one or more of trimethylolpropane tris[3-(2-methylaziridinyl)propionate], trimethylolpropane triacrylate, and pentaerythritol triacrylate; The tetrafunctional UV crosslinking agent is a mixture of one or more of pentaerythritol tetraallyl ether and tetrafunctional polyester acrylate; The UV initiator is a mixture of one or more of 1-hydroxycyclohexyl phenyl ketone, diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthone and isopropylthioxanthone.

6. The substrate-free foam tape according to claim 1, characterized in that: The preparation method of the grid release film comprises: The UV resin liquid is transferred and coated onto the surface of the substrate layer by an anilox roller, and then UV initial curing is performed to initially form a resin grid layer with a grid structure on the surface of the substrate layer. The UV exposure during UV initial curing is 500~2000 mj / cm 2 ; The substrate layer with the resin grid layer formed on the surface is subjected to UV secondary curing molding; wherein the UV exposure during UV secondary curing is 500~2000 mj / cm 2 ; A release agent is coated on the surface of the grid structure of the resin grid layer to form a release layer.

7. A substrate-free composite tape, characterized in that: The substrate-free foam tape comprises the substrate-free foam tape according to any one of claims 1 to 6, and further comprises a pasted layer, wherein the pasted layer is bonded to the foam layer.

8. The substrate-free composite tape according to claim 7, characterized in that: The laminated layer is a copper foil layer.

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